How much accuracy is gained by an inch of barrel?


PDA






Potatohead
May 5, 2013, 06:59 PM
Hey all..i know the answer of this question is probably hard to really prove but i know most of you experienced shooters probably have some good opinions on how much accuracy you gain by an inch of barrel? im sure their is tons of variables, among them how much barrel length are you starting with etc...im wondering because im really interested in the walther ppq m2 in 5", but the 4" looks much more balanced and of course would be easier to conceal. i know that accuracy mostly depends on the shooter but i just really want the shootability of a longer barrel...but being able to carry it every day would also be a plus, so im waffling on which to decide on. Does another inch really matter? (i know im opening up for a lot of sexual barbs here, but please dont get me kicked off the site:)

If you enjoyed reading about "How much accuracy is gained by an inch of barrel?" here in TheHighRoad.org archive, you'll LOVE our community. Come join TheHighRoad.org today for the full version!
Sam Cade
May 5, 2013, 07:08 PM
For the most part, mechanical accuracy isn't a function of barrel length.

giggitygiggity
May 5, 2013, 07:09 PM
I'd say the accuracy would be better because of the longer sight radius rather than another inch of barrel.

Fishslayer
May 5, 2013, 07:28 PM
I'd say the accuracy would be better because of the longer sight radius rather than another inch of barrel.

^^^ This.

Vern Humphrey
May 5, 2013, 07:32 PM
How much accuracy is gained by an inch of barrel?

Quick answer -- none. Accuracy has nothing to do with barrel length.

In practice, however, sight radius is a key factor in accurate aiming. A handgun with a long sight radius will be easier to shoot accurately than one with a very short sight radius.

In Elmer Kieth's famous use of Harold Croft's highly-modified Colt SAAs, he hit a 4X4 foot target at 700 yards with all four guns. With the 2 1/2" barrel gun, it took him 12 shots to get on target. With the 7 1/2" barrel gun, he hit it five out of six shots.

jmr40
May 5, 2013, 08:21 PM
In Elmer Kieth's famous use of Harold Croft's highly-modified Colt SAAs, he hit a 4X4 foot target at 700 yards with all four guns. With the 2 1/2" barrel gun, it took him 12 shots to get on target. With the 7 1/2" barrel gun, he hit it five out of six shots.

That pretty well proves that a longer sighting radius is more accuates. The 2 1/2" gun hit the target only 8% of the time while the 7 1/2 gun hit 83% of the time.

We all know the barrel length does not effect mechanical accuracy, but because of the longer sighting radius it is an aid in aiming. In effect, yes longer barrels are going to produce more accuracy when shot with iron sights. With optics, there would be no difference.

Exactly how much is hard to say, but everything else being equal 1 more inch of barrel length (sighting radius) will be more accurate. Things are not always equal though. Some guns are simply more accurate than others even with equal length barrels (sighting radius). It would be entirely possible for me to shoot a 3" gun to shoot more accurately than a 4" gun if the shorter gun is mechanically more accurate.

SharpsDressedMan
May 5, 2013, 08:32 PM
In some instances, a shorter barrel even ends up being more accurate due to barrel harmonics, flaws in the steel, and, in general, less flex from a shorter barrel.

Walt Sherrill
May 5, 2013, 08:34 PM
I'd say the accuracy would be better because of the longer sight radius rather than another inch of barrel.

Accuracy is one thing -- it's pretty much a mechanical thing. Shootability (and the ability to shoot the gun to it's fullest potential) is another. (And with long guns, other factors come into play -- as noted above.)

A longer barrel doesn't make a gun more accurate. It does help increase the performance of a given round - the speed with which it leaves the barrel...

A longer sight radius can make the gun easier to shoot well, but that's a gun/person interface thing, and not a function of the gun's innate accuracy. It's sort of like good triggers: they don't make the gun more accurate, but help the shooter take advantage of what's there more easily.

Put the gun in a Ransom Rest and test it, and you'll find it's accuracy. Put the same gun with a longer barrel in the Rest and test it, and you'll not likely see much difference if all other things are essentially the same.

A shooter MIGHT find the longer-barreled gun easier to shoot (i.e., easier to hit the target) -- but a good shooter with good eyes might not care that much, one way or another.

Walkalong
May 5, 2013, 09:10 PM
That pretty well proves that a longer sighting radius is more accuates. The 2 1/2" gun hit the target only 8% of the time while the 7 1/2 gun hit 83% of the time.It proves that it is easier to hit with a longer sight radius.

Peter M. Eick
May 5, 2013, 09:13 PM
I would agree with this.

If I really concentrate, I can shoot my 2.5" detective special as well as I can shoot my 8 3/8" Pre-27.

It is just easier to shoot the 8 3/8" pre-27 more accurately. The key is ease.

The guns are truly equal accuracy I believe.

SlamFire1
May 5, 2013, 10:14 PM
I think we all can agree the inherent accuracy of a pistol is not a function of barrel length.

But sight radius matters if you are using irons.

I can keep all of my shots on a 12" gong target at 25 yards with a 38 Spl Detective Special with a 2" barrel. I shoot standing, not off a bench. I do not have the same hit probability at 50 yards with the same target, I am doing well to hit the target one to two times out of six shots. With a 4" Colt Police Positive, the same action with a 4" barrel, I have to work at it, but I keep all six rounds on target at 50 yards.

I have experimented with 3" barrels, 5" barrels, and 7.5 inch barrels. My hit probability goes up with 3" barrels compared to 2", 5" barrels are slightly better at 50 yards than a 4". The 7.5" barreled pistols have a high hit probability all the way out to 100 yards.

I think a 5" barrel is the best all around for open carry, but sometimes you just have to make do with smaller concealed carry sidearms.

herkyguy
May 6, 2013, 09:40 AM
sight radius makes the difference. I switched from a 4" barrel G23 to a 3" barrel XDsc a few years ago in my HD pistol and noted a significant decrease in accuracy. i don't think it had anything to do with the manufacturing, but rather the decreased sight radius.

Potatohead
May 6, 2013, 02:17 PM
I got called to work and havent been able to catch up reading this yet but wanted to thank evryone for posting

Kp321
May 6, 2013, 02:44 PM
Yes, longer sight radius can lead to more accurate shooting but another factor is barrel time on low velocity pistol rounds. Longer barrel=longer barrel time=more time for wiggle. Back when Bullseye shooting was the only game in town, the 5" 22's, Smith 41's or Hi-Standards, could be shot more accurately than the 7" models, all other factors being equal.

Potatohead
May 6, 2013, 02:57 PM
thx everyone. good info slamfire, thanks. that is very surprising to me, that it really doesnt technically add accuracy to the gun...i have to figure you all are correct, being more experienced than myself, but if it makes a round shoot straighter and helps you aim better, i guess it does make the gun more accurate...or maybe makes the shooter more accurate might be the way to term it...?

rugerdude
May 6, 2013, 03:18 PM
I've actually noticed the opposite effect with regards to my 1911 shooting. I used to own a 5" SA 1911A1 and a 5" Ruger 1911, and I shot them about equally well. I went and bought a Commander length (4.2") Sig Scorpion and I shoot it better than any handgun, period. Better than my 5.5" Ruger MkII Target actually (which still baffles me!).

Granted, it would be better if I was comparing a Sig to a Sig here, but I do all of my shooting offhand and I doubt the 1.5" group shrinkage at 25 yards is due to mechanical accuracy differences. I have noticed that the front sight on the 4.2" gun seem to fit more "tightly" in the rear notch and so it becomes easier to center naturally. This may be what is coming into play here, also perhaps the cool tan color and neat grips :D

Walt Sherrill
May 6, 2013, 03:43 PM
i have to figure you all are correct, being more experienced than myself, but if it makes a round shoot straighter and helps you aim better, i guess it does make the gun more accurate..

I'm responding to the bit I underlined, above. Your "But." comment above -- unless I've misunderstood your meaning -- disagrees with the bulk of what's been written or said.

I don't think anyone said a longer barrel makes a round shoot straighter. One responder said that with some barrels, longer means more potential for harmonic vibration, which can make accuracy worse. (Browning has a system to help with that in their rifles; I don't think it's a concern with handguns.)

Another responder noted that in Bullseye, a longer barrel coupled to slower/less hot loads, gives the shooter more time to move around, which increases the potential for human error. (I must admit, however, that THAT argument assumes a level of proficiency far beyond my scant talents... <sigh>)

A longer sight radius CAN help the shooter a bit, but in that situation it's the shooter who is doing better, not the gun. A telescopic sight might help the shooter, as well.

In both cases, If YOU aim better, it's not the gun that's more accurate, it's the shooter that's more accurate. The gun doesn't really care.

Vern Humphrey
May 6, 2013, 04:21 PM
I think a 5" barrel is the best all around for open carry, but sometimes you just have to make do with smaller concealed carry sidearms.
With my carry gun, a Kimber Custom Classic (MK I), a standard size M1911, I can ring a 12" gong all day long at 100 yards.

Arkansas Paul
May 6, 2013, 04:58 PM
but if it makes a round shoot straighter and helps you aim better, i guess it does make the gun more accurate...or maybe makes the shooter more accurate might be the way to term it...?

The last part is correct. It makes the shooter more accurate.

Wil Terry
May 6, 2013, 05:23 PM
For the most part, mechanical accuracy isn't a function of barrel length.
THIS IS THE COMPLETE and final answer to the question asked.

Potatohead
May 6, 2013, 06:01 PM
disagrees with the bulk of what's been written or said.

If you keep reading post, i asked if saying it makes the shooter more accurate was a better way to put it..im not about to disagree with all you experienced folks on a question like this..ive been shooting 3-4 months!

Potatohead
May 6, 2013, 06:05 PM
This may be what is coming into play here, also perhaps the cool tan color and neat grips

^^^^^^^^^^^ this is probably the reason i'd say!

Potatohead
May 6, 2013, 06:09 PM
It does help increase the performance of a given round - the speed with which it leaves the barrel.

I don't think anyone said a longer barrel makes a round shoot straighter.

I was assuming speed = straighter....maybe i meant "flatter"

Walt Sherrill
May 6, 2013, 06:32 PM
I was assuming speed = straighter....maybe i meant "flatter"

You're kind of mixing apples and oranges...

With a good gun, and uniform loads (consistency with round performance), the groups shouldn't be that different between a hotter or weaker load -- if you remove the "human" factor.

Hotter loads might mean the point of impact is different than with weaker loads, with the same weight bullet and design, but it doesn't necessarily mean that groups fired will be tighter/better just because the round is moving faster. Gravity affects each successive bullet in the same way -- so it's a constant in terms of accuracy.

I'm over-simplifying, but as long as the shooter can adjust the sights or change his/her point of aim, the likelihood of hitting the target shouldn't be that much different with hotter or weaker loads; if there is a difference (and you WERE talking about a longer barrel), it'll be more dependent on the sight radius than barrel length performance. (That said, I've seen target pistols with sights extended beyond the end of the barrel, to artificially increase sight radius. I guess that can work, too.)

WardenWolf
May 6, 2013, 06:40 PM
Longer barrel means more velocity and higher spin rate. This can mean faster time-to-target and less drift, particularly at longer ranges. A longer barrel thus can mean greater accuracy.

A longer barrel can also mean reduced accuracy, however. In designs where the barrel bows or otherwise moves on firing, a longer barrel can mean greater deviation at the tip, which results in wider groups.

Potatohead
May 6, 2013, 09:18 PM
thanks guys. ive gota thick head but im gettin it:)

VetPsychWars
May 7, 2013, 10:09 AM
My question would be, does that extra inch really enhance your ability to conceal it? With some holsters, like horizontal carry under the arm, perhaps so. Inside waistband? Not so much.

Tom

Potatohead
May 7, 2013, 07:07 PM
good point, i hope..because i really want the 5"

olderguns
May 8, 2013, 06:47 AM
We know its sight radius that gives the extra accuracy, but to have that longer radius you Must have a longer barrel, so in a way it is the length of the barrel that helps you aim.

pockets
May 8, 2013, 08:30 AM
but to have that longer radius you Must have a longer barrel,
Many target pistols have been made with sight extensions and a barrel shorter than the sight radius.
I seem to recall S&W including an extendable front sight on some of their model 41 pistols. It rode in a groove on the slide and could be extended well past the muzzle.
.

Blackstone
May 8, 2013, 09:59 AM
Not disagreeing with anything that's been said, but would the extra twisting from the extra rifling have a greater stabilising effect on the bullet?

Roadking Rider
May 8, 2013, 10:33 AM
Hard to come up with a definitive answer to your question. I guess that would depend on the pistols in question and the person pulling the trigger.
Speaking only for myself,I shoot my CZPO-1 every bit as good as my CZ75b with the inch longer barrel and seem to shoot my G26 as good as I do the longer barrel Glocks. Having said that when It comes to 1911's I shoot the full size much better than I do the shorter barrel models. I think the answer is always going to be is what gun works best for the shooter and not so much as the length of the barrel if we're only talking an inch.

Infidel4life11
May 8, 2013, 11:40 AM
In some instances, a shorter barrel even ends up being more accurate due to barrel harmonics, flaws in the steel, and, in general, less flex from a shorter barrel.
This^ longer well made barrels tend to shoot with more velocity, shorter well made barrels are more accurate. Sight radius is king.

Walt Sherrill
May 8, 2013, 12:04 PM
Not disagreeing with anything that's been said, but would the extra twisting from the extra rifling have a greater stabilising effect on the bullet?

Possibly. But the original question was about the effect of an extra 1" of barrel length. If you read through everything below, and the links, you might get the idea that there is likely to be little difference in that effect unless the barrel length is greatly changed -- and then mostly when the barrel is shortened to a point that stability isn't imparted. It's hard to assess how much extra accuracy/precision is gained from that additional barrel length.

Until someone does Ransom Rest tests of two guns that are very similar except for barrel length, this discussion boils down to our understanding of THEORY and our interpretation of that theory. Ransom Rest tests do away with the "human element" -- and the need to actually see the target or squeeze the trigger properly. Ransom Rest tests assess the gun's innate ability to put shots fired consistently in a small group. Sight radius is irrelevant.

American Rifleman apparently did this back in the 70's using a .44 magnum handgun round in a rifle. They shortened and recrowned the barrel, and tallied the results. They continued down until they were testing what was the equivalent of a short barrel, and then to the point that the round started to keyhole. Their results -- there wasn't a great difference until the barrel got so short that stability was impaired. Somebody out there may have these test results stashed away, somewhere.

If you go to Wikipedia, you'll find that twist rates tend to be optimized for a given bullet's weight, shape, and length -- and that makes me wonder whether shooting the same round in different length barrels would offer varying results with some guns -- but I've seen nothing about firing the same round in handguns that have 4" - 6" barrels. Here's the link: http://en.wikipedia.org/wiki/Rifling One interesting point made in the Wiki article concerns bullet size and weight. It says,

"Large diameter bullets provide more stability, as the larger radius provides more gyroscopic inertia, while long bullets are harder to stabilize, as they tend to be very backheavy and the aerodynamic pressures have a longer "lever" to act on."

Reading that, I wondered if that explains why BULLSEYE shooters seem to love .45 ACP -- and explains why some of the most impressive long-distance sniper shots have been made using .308 and .50 caliber rounds.

There is a formula for selecting the twist rate in the Wiki article -- and I wonder if the twist rates of a 4" pistol barrel differs from that used with a 5" or 6" barrel. We might find that different weight/bullet shaps/loads might make a difference, if the twist rates are the same. (The Wiki article also mentions the use of twist rates that change in a single rifle barrel -- that was something I had never heard of...)

In some tests I've found on the net (very precise, but focusing on air guns with rifled barrels), the relationship between velocity and twist rates seems to vary with lower power settings (corresponding to less powerful loads) doing better with lower twist rates, and higher power settings doing better with higher twist rates. That series of tests, however, uses a single projectile design and weight. None of the differences were significant until the target was pushed out to 25 yards or more -- and most of us would LOVE to be shooting the groups they were getting at those distances!!

A participant on another forum made the following observation; I added the underlining, below. Keep in mind, this participant describes accuracy as the ability of the shooter to shoot a gun well enoough to hit what's being aimed at, while precision describes the gun's ability to shoot small, consistent groups (ignoring the human element). That's not layman terminology, because we tend to call both things "accuracy" -- but there is a difference, and it's good to understand that difference. One has to do with the gun's innate ability to deliver, while the other has to do with the shooter's ability to take advantage of that innate ability. When we started this discussion some were talking about accuracy and some were talking about precision. I think the Original Poster was asking about precision, which is NOT the same as accuracy. This other commentator went on to say:

Shortening the length of a barrel will have a small effect on precision, which relates to the ability of a gun to shoot consistent, tight groups. Shortening the barrel length (within reasonable limits) will insignificantly alter the grouping ability of a gun, which means it will have an insignificant affect on precision.

Accuracy relates to making the point of impact the same as the point of aim. Since bullet velocity is highly affected by barrel length the bullet will drop more over a given distance as the barrel is shortened. Thus accuracy in hugely affected by barrel length because the point of impact will drop relative to the point of aim as the barrel length is reduced, IF THE SIGHTS ARE NOT ADJUSTED. If the sights are properly adjusted after shortening the barrel, the point of impact can be restored to the point of aim, thus restoring the accuracy.

Much longer barrels (rifles), as noted in this discussion, can bring with them their own problems, due to a lack of rigidity, expansion from heat, or barrel movement from vibrations (harmonics, etc.).

We do know that the extra sight radius of a longer barrel can help the shooter manage the gun better. As can a better trigger, and better-fitting grips, etc. Those are all things that make the SHOOTER more ACCURATE -- but the gun doesn't care. The gun's PRECISION is likely to remain the same, or close to the same unless the barrel length is greatly changed.


.

918v
May 8, 2013, 12:59 PM
Walther PPQ factory test target at 15m:

http://www.gun-tests.com/newspics/0312-Walther-PPQ-WAP00Q90-9mm-Lede.jpg

918v
May 8, 2013, 01:03 PM
http://i1191.photobucket.com/albums/z472/shootin40cal/40CalPPQFacotryTestTarget.jpg

918v
May 8, 2013, 01:05 PM
http://img.photobucket.com/albums/v335/Clipse3GT/3e1940a2.jpg

918v
May 8, 2013, 01:06 PM
http://i669.photobucket.com/albums/vv60/kk9zz/PPQfactorytarget.jpg

918v
May 8, 2013, 01:07 PM
http://i186.photobucket.com/albums/x49/roman3/IMG_6103.jpg

918v
May 8, 2013, 01:13 PM
Can't find any PPQ 5" test targets.

Potatohead
May 8, 2013, 02:00 PM
wow thats nice 918..beautiful gun..i assume you like it? feel free to offer any details

Potatohead
May 8, 2013, 02:04 PM
American Rifleman apparently did this back in the 70's using a .44 magnum handgun round in a rifle. They shortened and recrowned the barrel, and tallied the results. They continued down until they were testing what was the equivalent of a short barrel, and then to the point that the round started to keyhole. Their results -- there wasn't a great difference until the barrel got so short that stability was impaired. Somebody out there may have these test results stashed away, somewhere.

thats very interesting..and surprising to a newb like myself

Potatohead
May 8, 2013, 02:07 PM
wow! nice post Walt Sherrill

PRM
May 8, 2013, 02:32 PM
Not sure an inch would have a lot of impact on accuracy or performance - hasn't for me. I will say the three inch heavy barrel on my Model 36-1 tames the recoil and makes shooting it more of a pleasure over my two inch snubs. Concealment is not a noticeable factor in my carry. I usually carry a pancake style holster on my strong side. I have carried my two inch guns in ankle holsters. Don't have one for my three inch. If there is any difference, I would say it would probably be in this type of carry.

Bovice
May 10, 2013, 10:43 AM
What's the point of 8 million posts of walther factory test targets?

leadcounsel
May 10, 2013, 11:35 AM
My practical experience tells me that there is a world of difference in my practical accuracy between a 2 or 3" barrel and a 5" barrel. Perhaps a combination of:
1. Longer sight radius
2. Effectively doubling the length of barrel to double the stablization and spin on the bullet, which we all agree makes a bullet more inherently stable and accurate. It's not just 1" difference, it's a percentage. The increase from 2" to 4" DOUBLES the time in the barrel and adds more spin to the round, which must add some power and stability to the round as it exits a 4" barrel.
3. More powder behind the bullet, and more energy, rather than wasted energy escaping from the muzzle in a 'flash.'

I think there is a sweet spot of deminished returned for a pistol in size vs. compactness at 4" for a standard carry gun, and 5" for a home duty gun. Of course, the pistol cartridge probably performs best from a rifle, but if you're going to go with a rifle, then use a rifle cartridge.

brickeyee
May 10, 2013, 02:03 PM
The increase from 2" to 4" DOUBLES the time in the barrel and adds more spin to the round

you must have some pretty funny rifling, like gain twist.

Once the bullet enages the rifling the spin rate per length traveled is set.

Having a longer barrel with the increased in velocity that usualy results meas the spin rate per unit time will increase, but it is a losing battle on the stability side.

The higher velocity results in increased overturning force.

Potatohead
May 10, 2013, 02:21 PM
What's the point of 8 million posts of walther factory test targets?
I wondered that myself

herkyguy
May 10, 2013, 05:00 PM
here's a twist...... get a shorter barrel but put some high-quality target sights on it. i have a few guns with longer barrels but have more or less maxed out their practical accuracy due to the large size of the front dot. now that messes up the whole conversation!

Vern Humphrey
May 10, 2013, 05:10 PM
Use Patridge sights, not dot sights on handguns. The Patridge, with it's wide, flat front sight is sighted to place the bullet just on top of the front sight, centered,

918v
May 13, 2013, 11:17 AM
What's the point of 8 million posts of walther factory test targets?

The point is to show an unbiased baseline for accuracy. I could not find any 5" PPQ targets. As soon as I do I'll post them.

1SOW
May 14, 2013, 02:54 AM
1" of additional bbl length 'can' increase a "gun's" accuracy. It depends on the original length of the bbl.
USE .22lr or 45 ACP as an example (often used for bullseye target comp.):
A 3"-4" bbl pistol in a ransom rest will not be as accurate as a 4"- 5"" bbl in a ransom rest. More accuracy improvement can be seen normally at about 5" +.. Bullet Ballistics improves quite a bit with added bbl length up to a point.

As said throughout the thread: Sight radius , pistol weight and other factors also make it easier to shoot accurately.

Walt Sherrill
May 14, 2013, 10:59 AM
A 3"-4" bbl pistol in a ransom rest will not be as accurate as a 4"- 5"" bbl in a ransom rest. More accuracy improvement can be seen normally at about 5" +.. Bullet Ballistics improves quite a bit with added bbl length up to a point.

You may be correct, but most of what has been shared in this discussion suggests otherwise. I'll repeat some of the points already made... Unhappily, I've never seen Ransom Rest test results assess that single variable. I've seen them for specific guns, and seen them used to compare one custom gunmaker's version of a given model (ala 1911) to another gunmaker's creation.

A Ransom Rest takes the human variables out of the mix, so that finger on the trigger and sight/target alignment aren't factors; the test simply assesses the gun's ability to return to the exact same starting position for each shot -- demonstrated by small groups when the gun is fired. They're useful for steel-framed guns, but can't be used with most polymer-framed guns.

The information shared here suggests that if everything but the barrel length is the same, the results of a Ransom Rest test might not differ greatly between longer or shorter barreled guns, until barrel lengths are quite different. If we're talking only about an inch or two, the "improvement" in performance due to higher bullet speed and spin rate, etc., may not be significant. It may depend on the load.

The American Rifleman article previously mentioned did an equivalent test - took a handgun caliber rifle with a long barrel and started lopping it off, an inch or so at a time, recrowning the barrel, and retesting. They didn't notice much change in precision/group sizes until the barrel got so short as to impair the stability of the round. There were differences of course, but they were not profound. (I'm looking for the original article; all I've read are summaries that may be inaccurate.)

At closer ranges, like those most often encountered in self-defense situations, barrel lenght might not matter. I wonder how much of self-defense shooting is truly "aimed fire" -- a lot of it seems to be variations of "point-shooting" or just blasting away. I suspect that if the shooter uses the sights, the longer sight radius of the longer barrel will help the shooter as much as any improved round performance from that longer barrel.

powder
May 14, 2013, 11:50 AM
Depends. :neener:

Potatohead
May 14, 2013, 12:46 PM
thx for your comments fellas

Walt Sherrill
May 14, 2013, 03:36 PM
I found the following on the S&W Forum, among discussions between Bullseye shooters. They were talking about revolvers, but I suspect some of the concerns still apply to semi-autos that have locked-breech designs (or fixed barrels).

One of those responding earlier mentioned the effect of harmonics and vibrations -- and this shooter also feels it's important with short pistol barrels, too. The barrel and slide, in a locked breech system, has already begun to move before the bullet leaves the barrel, but the barrel/slide hasn't moved far. It is probably influenced by harmonic vibration in a different way than is a fixed barrel, but still infuenced.

I added the underlining and bolded characters, below.

From a purely engineering standpoint, with a one piece barrel the shorter barrel will actually be more accurate than a longer barrel. When a barrel is attached to the frame at just one end it becomes in effect a Cantelever Beam. Since a bullet transitting the barrel will cause that beam to bounce like a diving board, a shorter barrel will be "stiffer" in it's response and the end will deflect less during the transit event. I suspect that if a 2 1/2 inch 686 and a 6 inch 686 were both equipped with a good handgun scope and fired from a rest by a real good shooter, the short barrel would just trounce the longer barreled gun in group size. However, in order to prove this out completely, each gun would have to use a load that was optimized for the barrel length. Because Harmonics can have a distinct effect on any vibrating system and barrels do vibrate in response to a bullet transitting them. Ideally you want a load and bullet mass where the end of the barrel is passing through it's Neutral position when the bullet exits the muzzle. Ask anyone who's worked up loads for long range rifle shooting, just a 100 fps difference in velocity can make a distinct difference in group size downrange.

There are other comments which indicate that some top-flight shooters prefer and shoot shorter-barreled guns better than longer-barreled guns -- even when they're competing against shooters using those longer barrels.

.

Vern Humphrey
May 14, 2013, 04:13 PM
There is a problem with that -- if we assume the barrel that is "bouncing like a diving board" is following a sine wave pattern, then the effect can be either beneficial or negative. If bullets are exiting at the top or bottom of the wave, the gun will be very accurate -- because there is very little motion at that point.

On the other hand, if bullets exit between nodes then accuracy will be poor.

You may remember Browning used to offer a device on the barrel to "tune" the barrel to the harmonics of your load. That's how it worked -- as you turned the device one way, if groups got smaller, it meant the harmonics were being tuned so bullets exited at the node.

Target008
May 14, 2013, 05:36 PM
in my experience not much and that can include some really large jumps like 3"-6" now while i do not personally believe that much accuracy is gained velocity on the other hand is a different story.

1SOW
May 16, 2013, 02:52 AM
The information shared here suggests that if everything but the barrel length is the same, the results of a Ransom Rest test might not differ greatly between longer or shorter barreled guns, until barrel lengths are quite different. If we're talking only about an inch or two, the "improvement" in performance due to higher bullet speed and spin rate, etc., may not be significant. It may depend on the load.

I don't disagree. The word "greatly" is included above. The point was the would adding an inch to bbl length improve accuracy. My point was that depends on the starting length. AT ONE EXTREME: A one inch bbl (I had one--a 5-shot stainless 22 lr revolver ) will not get the accuracy as a two or three or 5" bbl in the same pistol with any load.

Velocity does matter, and discounting that as a factor included with a longer bbl is ignoring the facts. The OP didn't say or ask about velocity.
"Handgun Ballistics per inch of barrel" is an amazing test of virtually all calibers of handguns from .22 to 460 Rowland. using "FIXED" bbls from 2" to 18". Amazingly long distances in the bbls showed continued acceleration and resulting spin of the bullets.
http://www.ballisticsbytheinch.com/

"Pocket Pistols" atre not going to perform as well a longer bbl pistol. There isn't enough bbl twist to fully stabilize the bullet. I would suspect one specific bullet weight would show the optimum accuracy in that gun. Adding an inch here can make a difference in accuracy dmonstrated with longer ranges..

See how many Bullseye pistol shooters use a three inch or less bbl at 25yds or more. They would if they were more accurate. Yes, I know, but there are shooters that can hold the 3" sight radius on target with a balanced/weighted pistol..:D

Would make an interesting test in a specific pistol with maybe three typical loads of light, medium amnd heavy charges..:cool:

Walt Sherrill
May 17, 2013, 06:56 PM
Velocity does matter, and discounting that as a factor included with a longer bbl is ignoring the facts. The OP didn't say or ask about velocity.
"Handgun Ballistics per inch of barrel" is an amazing test of virtually all calibers of handguns from .22 to 460 Rowland. using "FIXED" bbls from 2" to 18". Amazingly long distances in the bbls showed continued acceleration and resulting spin of the bullets.
http://www.ballisticsbytheinch.com/

That is an interesting site and I've bookmarked it. Thanks.

Unless I missed, it however, it doesn't address a relationship between muzzle energy and accuracy/precision. It just shows what energy is gained for specific changes in barrel lengths. You seem to feel there is a relationship.

I did a quick spreadsheet on the data for 9mm Luger -- for 4, 5, and 6" barrels. Generally, the increase in muzzle energy moving from 4"-5" is roughly 1%-2%, and from 5" to 6" roughly 4%-6%. The biggest jump (from 5" - 6") -- that seems to be the sweet spot.

If you run the spread sheet on out, you'll see that the energy increase with each added inch of barrel is smaller, and at 18" length, for most loads, muzzle energy actually decreases

In the case of the 4"-5", a 1%-2% improvement in muzzle velocity isn't likely to be noticed; the from 5" to 6" is more meaningful, but I'm not sure it translates to a comparable increase in accuracy.

In the case of .45 A.C.P, the results were a little different, with the biggest increase coming in the 4"-5" jump (from 2%-7%, depending on the load), but less with 5"-6", where it varied from 0% to 3%, Muzzle energy generally increased with increased barrels, lengths -- but as with 9mm, at a decreasing rate, and actually declined at 18".

How do we correlate muzzle energy to accuracy/precision? Got any other sites? All of this would seem to suggest that for some rifles firing pistol cartridges, barrel length should be something to which the shooter/buyer pays close attention. And, as others have noted, bullet weight and design may be a critical factor, too.

.

Walt Sherrill
May 18, 2013, 10:28 PM
Since replying, above, I've done a lot of digging on the web and found basically nothing except anecdotal evidence that addresses the relationship of barrel length or muzzle energy to accuracy. I did find this interesting comment on the S&W Forum, where one member responded to another's claim of calculations that showed that a 3-4 inch barrel would give larger groups than a 5 inch barrel. That person said there was a calculation, but didn't share it, and didn't give evidence that could be verified. The responder said:

It is just barely possible that in the 3 - 4 inch barrel range, the mathematical calculations are relevant. However, in the summer of 1931, then-Major Julian Hatcher fired a "possible" at the British Nationals at Bisley with an H&R pistol with 8" barrel rather than the customary 10" barrel, with Ensign Harry Renshaw taking second place with a 98, using the same H&R pistol. The following year, interest in short-barreled H&R pistols increased considerably. Walter Roper subsequently did a limited study of the effect of sight radius on accuracy (three shooters, extensive shooting with more than one sight radius), and concluded, IIRC, that the shorter sight radius was better for one (top) shooter, longer for another, and unclear for the third. Roper reports all of this in his book Experiments of a Handgunner. There was also published an article by him in the September 1946 American Rifleman, in which he noted that after over a hundred shooters purchased short-barreled H&R pistols, a majority of the 65 who reported back to him reported better scores with the short pistol.

It seems quite clear to me that the arithmetic involved is often less important than other variables in the individual shooter, and the actual practical result can usually be determined only by extensive experimentation.

That was a long time ago. Now, many Bullseye shooters and handgun hunters seem to believe that OPTICAL SIGHTS (scopes, red dots, etc.) make sight radius an unimportant variable.

They also seem to feel that if not using optical aids, some barrel lengths might be better with a given pair of eyes, than another. Then note, too, that many (perhaps most) factory handgun loads come optimized for the fairly standard 4" barrel. -- and that in all cases, that optimal performance will come only when the load used is FITTED to the a bullet weight and shape, barrel length, and twist rate.

In the case of rifles, it appears that longer barrels are absolutely greatly superior when shooting at ranges beyond 250 yards (or far longer) -- as much as because they are more likely to reach out that far as for the ability to group -- but that much shorter rifle barrels can be just as (or more) precise at closer distances (100-250 yards).

Nobody seems to any hard data. (I can't find it... it may be out there.)

Vern Humphrey
May 18, 2013, 10:42 PM
There was also published an article by him in the September 1946 American Rifleman, in which he noted that after over a hundred shooters purchased short-barreled H&R pistols, a majority of the 65 who reported back to him reported better scores with the short pistol.
He might have been seeing the Hawthorne Effect -- they bought the shorter barrels expecting better scores and they got better scores.

Walt Sherrill
May 18, 2013, 10:51 PM
RE: Hawthorne Effect.

Could be, but it works the other way, too, doesn't it?

Vern Humphrey
May 18, 2013, 11:10 PM
Yeah -- but no one buys a gun expecting to shoot worse, so the sample consists almost entirely of people who expected to shoot better.

Walt Sherrill
May 19, 2013, 11:22 AM
Yeah -- but no one buys a gun expecting to shoot worse, so the sample consists almost entirely of people who expected to shoot better.

Expectations can drive a lot of results. Your statement above could also be applied to those who KEPT their existing weapons or decided to buy 10" barrels, too. They wouldn'tve bought or kept their 10" guns expecting to do worse...

The Hawthorne Effect really addressed GROUP DYNAMICS and GROUP PRODUCTIVITY and the PERFORMANCE OF TEAMS working on group objectives. In the cases I've cited earlier, there were no teams, just individuals reporting their changed scores -- and it may be that they were unaware of how others using the same barrels were doing...

.

Vern Humphrey
May 19, 2013, 06:32 PM
Expectations can drive a lot of results. Your statement above could also be applied to those who KEPT their existing weapons or decided to buy 10" barrels, too. They wouldn'tve bought or kept their 10" guns expecting to do worse...

Perfectly true -- but the informal study cited above included only people who bought shorter-barreled guns.
The Hawthorne Effect really addressed GROUP DYNAMICS and GROUP PRODUCTIVITY and the PERFORMANCE OF TEAMS working on group objectives. In the cases I've cited earlier, there were no teams, just individuals reporting their changed scores -- and it may be that they were unaware of how others using the same barrels were doing...
Actually not -- most of the Hawthorne employees had repetitive tasks and worked on piecework.

Walt Sherrill
May 19, 2013, 10:47 PM
Actually not -- most of the Hawthorne employees had repetitive tasks and worked on piecework

Piecework was one of the variables after the initial study was expanded. It went on with a small group of women for a much longer period, and that's where they started to see really interesting results.

Nearly every article you can find about the Hawthorne effect discusses it as an important milestone in industrial and organizational psychology. It's generally described as being about group dynamics and how management interventions -- some seemingly meaningless -- can affect group behavior and performance. The Hawthorne workers initially had NO EXPECTATIONS of performance improvements, but they quickly learned they were being watched. THAT can affect performance.

As the studies progressed, the workers were given a lot of feedback, and even had opportunities to suggest changes. At one point, workers were paid based on group performance rather than individual performance -- piecework standards went out the window for a while; they were even allowed to change the length and frequency of breaks and the duration of the work day. Generally, performance improved, regardless. Sometimes it improved even when things went back to an earlier state or condition. It was all about being observed and getting (and, perhaps, giving) feedback.

Unlike the workers in the Hawthorne study, the shooters we're talking about were queried AFTER the fact. The fact that some shooters did better because they expected to do better is a real possibility -- a self-fulfilling prophecy, so to speak -- but it may also be that the shooters who went to the shorter barrels got better because they were the ones who were trying harder, or because they were learning and improving with practice and the experience they gained from an additional year of matches. They may have improved with 10" barrels, too.

After posting that "statistic" I mentioned, I got to thinking about what it really told us: that 100 were queried and only 65 responded. Of that 65, it could be that as few as 33 saw improvement. That, in turn, could mean that as many a 67 of the 100 (i.e., 32 + 35) may NOT have seen any improvement.

Statistics can sometimes be interpretations (and intensely subjective). Or, as Mark Twain called it: "Lies, Damned Lies, and Statistics."

Vern Humphrey
May 19, 2013, 11:19 PM
After posting that "statistic" I mentioned, I got to thinking about what it really told us: that 100 were queried and only 65 responded. Of that 65, it could be that as few as 33 saw improvement. That, in turn, could mean that as many a 67 of the 100 (i.e., 32 + 35) may NOT have seen any improvement.

Statistics can sometimes be interpretations (and intensely subjective). Or, as Mark Twain called it: "Lies, Damned Lies, and Statistics."
All perfectly true -- which was my point. The "study" which found there might be an improvement from a shorter barrel showed no such thing, and improvements may have come because the people who bought shorter-barreled guns expected to improve.

If you enjoyed reading about "How much accuracy is gained by an inch of barrel?" here in TheHighRoad.org archive, you'll LOVE our community. Come join TheHighRoad.org today for the full version!