Ideal barrel length for a 22LR

[ShaiVong]

I bought a box of subsonic rounds for my 22lr just to give it a try. I was sighting in my Ruger 10/22 that i just bought, grouping pretty good at 50 yards. Maybe 1"-2" groups. I tried the subsonic rounds after my CCI rounds, and the group spread way out. I still have a box of 40 subsonic rounds, i think ill have that box for years

 

[JohnBT]

Unless you cleaned the barrel, that's to be expected when you change ammo. It could take anywhere up to 30 or 40 rounds for the new ammo to lay down a good layer of the new lube in the barrel. Could take 5, but you never know until you shoot them. Give them a chance. Why save them?

John

 

[MacPelto]

One trend in international 3 position smallbore is towards shorter barrel lengths with 'bloop tubes' attached. This allows a longer sight radius with the short barrel length. Velocity is not the reasoning behind this, however. The advantage is that the bullet spends less time in the barrel, being pushed off course by the body movements of the shooter. This may or may not be useful information, but it takes place in every rifle.

 

[ShaiVong]

I'm still trying to understand the relationship between barrel length and accuracy vs velocity, this thread is really helpfull.

Wouldnt you get more spin on your bullet if it traveled through a longer barrel? Isnt more spin better? Like a gyroscope?

Now that we have discussed the different properties, I have to ask:
Which is a more accurate barrel for a 22? 16" or X>16"

 

[9mmepiphany]

spin stabilizes the bullet... but once spin has been imparted, additional time in the barrel is a greater liability unless your followthru is perfect.

the real advantage of the longer barrel is balance and sight radius. the accaracy of a barrel has more it's chamber demensions, quality of the rifling and harmonics

 

[444]

ShaiVong
To sum up some of what has been said;
Velocity; In a .22LR there is a point where the maximum velocity is achieved. After that point the friction between the barrel and the bullet actually decreases velocity. Appearently the max velocity occurs at 14". In a rifle, a barrel this short requrires a federal tax stamp, so the best comprimise would be a 16" barrel. This would give you the most velocity for a non-NFA weapon.
Accuracy: The reason that a longer barrel is more "accurate" than a shorter barrel is simply because the sights are further apart which decreases the human error in sighting. Obviously this is only a factor with iron sights and only is a factor if the rifle utilizes the additional length. A rear sight mounted at the rear of the action is better than a rear sight mounted half way down the barrel as far as accuracy is concerned. With a scope, barrel length isn't a factor.
Spin: The amount of "spin" required is enough to stablize the bullet. This is determined by the length of the bullet. A given rifling twist will stablize a range of bullet lenths, deviate from that and you won't stablize the bullet. Once the bullet is stabilized, allowing it to "spin" in the barrel provides no benefit.

Please feel free to correct any errors I have made.

 

[9mmepiphany]

444 - a very nice summary

i remember an article awhile back in an annual (like gun digest) about the shape of the barrel, in cross-section affecting a barrel's potential. the optimum shape for the .22RF looked like a bell-shape with the opening facing downward

 

[ShaiVong]

Very nice 444.

Don't you want the bullet (in a 22) subsonic when it leaves the barrel though? I would think that a supersonic bullet that goes subsonic would be more accurate, especiallly on a breezy day, than a slower subsonic bullet which doesnt have nearly as flat a trajectory.

 

[444]

This I am not as well versed on, but to answer your question; No. It has to do with a turbulance that is created when the bullet goes from supersonic to subsonic. This creates some inaccuracy. How much, I don't know. Obviously if you are shooting inside the distance that it takes the bullet to go subsonic, it isn't an issue. I first learned of this when I dabbled in rimfire silhouette. I thought along the lines that you did. Since you shoot out to 100 meters, you would want the flattest shooting round you could get. But in reality, you make up for the greater trajectory by simply adding more windage to your sights, and the bullet is more accurate to boot.
So, the most accurate .22lr ammo made today is subsonic at the muzzle. However the difference is lost on mortals like me. But if you can shoot well enough to appreciate it, subsonic is the way to go in a .22lr.

 

[twoblink]

If you are using iron sights, then it's a great question..

You lose a lot of velocity out of a 24" barrel... But you gain quite a bit of sight radius..

I think 16" is great, but I like a good 22" sight radius...

 

[ShaiVong]

Sight radius doesnt really matter to me, atleast on my 22, because i use a scope.. My eyesight is bad enough that at less then 50 yards i cant really see the target anyway , if its smaller than a basketball that is.

 

[AStone]

As a proud new owner of a Marlin 39A (with 24" barrel),
I'm subscribing to this information ladden thread.

Even before I bought this little sweet heart of a rifle,
I'd been thinking that once I got one,
I'd have the barrel cut down.

A 24" barrel, I thought,
would be just absurdly long
for a rimfire. What's the point?
(Yeah, yeah: sight radius. I'm going to scope it.)

Indeed, when today, I picked it up for the first time,
I said to myself, "Self, this is the right .22 rifle. Buy it."

and

"It's front end heavy. Get it cut down."

Now, the person who sold me this 39A, a gunsmith,
asserted that I can't cut it down much less than about 3"
because it has a magazine tube attached to the barrel
3.5" back from the end of the barrel.
If I cut it back more than that,
then re-attaching the magazine tube to the barrel
becomes very expensive.

Still, a 21" barrel seems more reasonable
(and no less accurate) than a 24" barrel.

Thus, I'm reading with interest.

Nem

 

[Mal H]

Ok, Nem, here are some facts as determined by me and my own chronograph. I set out to see if a longer barrel does indeed slow down a .22 bullet. I decided to use Colibri ammunition since it uses no powder, only priming compound, and therefore the friction aspects of the barrel would (should?) be greatly magnified.

The test firearms were the only ones I owned at the time in .22 LR: a 5 1/2" Ruger bull barrel, MK 512; a 20" 10-22T; and a 24" Marlin 39AS.

The results went against the conventional wisdom that a longer barrel will actually slow down a bullet since it has gone past the point of acceleration inside the barrel and is starting to slow down somewhere before exiting the muzzle. My experiment doesn't disprove that theory but it does show, for my ammunition choice and my guns, that the optimal length is at least 20" or longer.

The test results:

5 1/2" barrel
Avg vel = 405 fps
Std dev = 23.2

20" barrel
Avg vel = 418 fps
Std dev = 20.6

24" barrel
Avg vel = 426 fps
Std dev = 15.4

So, don't cut down that 39A barrel in order to gain velocity. (I think it would be a sin to cut it down anyway for any reason, but that's not my call.)

Now, the ideal experiment along these lines would use the same barrel, same lot of ammo, same environment conditions, etc. An inch would be cut off and the barrel recrowned for each run. Someone or some group has done that IIRC, but I don't know what the caliber was and what the findings were. I don't think it was .22 LR, however.

 

[cheygriz]

Mal,

IMHO, a chronograph test would only be valid if you used the same firearm, with the same barrel, and progressively cut off oone inch at a tims and chronogrqphed it. Different barrels from the same manufacturer will gove different velocities.

MY 20 inch barrel custom .30-06 consistently shoots 150 FPS faster than my 24 inch barrel 12903A3 Springfield.

 

[Mal H]

cheygriz, I believe that's what I said in my ending paragraph.

 

[tubeshooter]

Congrats Nem, I know you've been waiting patiently for that 39A.


I don't know if your mind is already made up.... but try giving it a spin as-is before you cut it. And let us know how it handles and performs if you *do* end up cutting it, please. Thanks....

 

[AStone]

Mal & Cheygriz, thanks for the input. Even if it doesn't solve the issue definitively, it's still relevant.

I guess you're probably both right: same gun, same ammo, same conditions of temperature, etc, cut barrel one inch at a time and chrono it. (Nope, not me, but it is a valid experimental procedure. We'll have to see if we can find that paper that Mal spoke of where someone may have done just that.)

Anyway, this continues to be an interesting discussion. I hope we continue with it.

Tubeshooter, thanks. I'll definitely be shooting it for a while before cutting it down ... if I do cut it down. I haven't decided with certainty to do that. That's a big and irreversible decision. I'll take my time with it.

And finally, Mal, my decision is not really based so much on velocity decisions as on balance, pointability and length for carrying in thickets. I just have this thing for shorter long guns, as long as they get the job done. I'm not going to be punching paper at 100 m with this one, but mainly shooting squirrels at 10 - 50 m.

Still, I hear you about the "sin" part.

But then, I'm not a religious person.

Thanks all.

Nem

 

[cheygriz]

I think Nema has some valid points.

If you're gonna use a .22 for formal competition, then 22 or 24 inch "musket" barrel is the only way to go.

OTOH, if you want a fast handling, lighteight, easy to carry little trail and hunting rifle, a barrel of 16 inches, or 18 at the absolute max is the way to go.

IMHO, the finest little .22 hunting, plinking, and trail gun ever made was the old Marlin 39 "Mountie." Short, light, straight stock, lightning fast to shoulder,... in short, the nearly ideal .22. Just my $.02!

 

[AStone]

I agree about the mountie for all reasons but one: I just don't like straight stocks.

All the long guns I've ever had have been (still are) pistol grips.
I've spent probably a few hours in gun shops over the years, just trying out straight grips.

For some (probably irrational) reason, they just don't melt my butter.
Every time I have the same response: put it back.

If the mountie was still made and with a pistol grip, I'd probably snap one up.

 

[JustsayMo]

Here's some comparitive data on barrel length/velocity that I did a while back. Except for the Aguila subsonic ammo the longer barrel always produced the highest average velocity though the difference was quite small.

Marlin 39A- 24" Barrel
Marlin 39A Mountie- 20" Barrel
Marlin 39TDS- 16" Barrel

The Ammo
Fedral 550 Bulk Pack ammo, 36 grains HP bullet, copper "plated"
39A : Average velocity 1263 fps (Highest was 1283, lowest was 1237)
Mountie Average 1254 fps (hi 1297, low 1230)
39TDS Average 1251 fps (high 1292, low 1216)

Notes: claimed velocity on box says 1280. This ammo shoots well in a wide variety of my rimfires, including autoloaders. The accuracy is very good in all of my Marlins.

Aguilla SE Subsonic 38grains lead hollow point
39A average 984 (high 1000, low 937.2)
Mountie average 994 (high 1023, low 984)
TDS average 1007 fps (high 1024, low 993)

Notes: This ammo has proven to be accurate in a wide variety of my rimfires. Only Match ammo has surpassed it in guns that shoot it well. It does NOT cycle any of my autoloaders. On most days this ammo will produce the best groups. Today it was true in my 39A and Mountie. Interestingly the 16" Barreled 39TDS produced the highest Velocity with this ammo.

CCI CB Longs 29g RN lead
39A (it was hard to tell these even when off in this gun) 677 avg (681 high, 668 Low)
Mountie 675 avg (720 high, 636 low)
TDS 668 average (674 high, 652 low)

Notes: Only the TDS (1/2" @ 25 yards) and my Single Six shoot this what I would consider "well". The Mountie shoots it OK (~1" at 25 yards). Most of my rimfires do NOT shoot this well. It is very quiet in long barrels.

CCI Mini Mag 40g copper coated, solids
39A 1255 avg (1272 high, 1230 low)
Mountie 1225 avg (1243 High, 1191 low)
TDS 1221 avg (1244 high, 1202 low)

Notes: Of my three 39's the Mountie shoots this the best. It is a little less accurate than the Fedral Bulk at more than twice the cost so I rarely use it.

 

[AStone]

Related thread updated.

The 24" barrel on this Marlin 39A feels too heavy.
The rifle is definitely a keeper. (And haven't even shot it yet.)

But the barrel is too long and front-end heavy.
Beyond data, my intuition tells me so.

I've been doing some reading tonight about the importance of "balance" in rifles.

Not velocity as a function of barrel length, or hyper- v. sub-sonic ammo, but balance.

What I'm learning is that balance may be more important to accuracy than ... all that other stuff.

This 24" barrel doesn't balance well for me. YMMV.

I'm thinking 18" to 20" will balance better.

 

[JustsayMo]

Nema,
The original poster wrote;
"Anyone know what the ideal barrel length is for a 22LR before you start losing velocity from the bullet-barrel friction?"

Are you trying to hyjack his thread and make it a discussion about what balances?

 

[AStone]

Just suggesting another dimension to the discussion, J'Mo.

 

[cheygriz]

And, of course, the more dimensions a thread has, the threadier it becomes!

And I hate hanging by a thread that isn't thready!

 

[mp510]

You'll get maximum velocity out of 16". If your shooting iron sights, the longer the better- simply because of the increased sighting radius. For some of the fancy olympic type rifles, they have 16" barrels and detachable false muzzles that are used to extend the sight radius.