9mm, .40 S&W, .45 caliber accuracy potential

[tfk]

I would like to discuss my findings and also some hypothesis. I hope I am right, if I say that .45 ACP is maybe the most favourite pistol caliber for disciplines where accuracy really matters. Let's put aside .32 SW because it's different league in accuracy due to fixed barrel. I wondered why people swear by .45 so often in terms of accuracy, whether it's due to popularity of 1911 platform or the cartridge. I am in a process of upgrading my press, mainly the powder measure system. It's no surprise that some powders meter better than others. I have measured two different powders which I use for reloading 9x19 and one meters with precision +-0.03 gr and the other one with precison +-0.015 gr (AA2). It is logical that everyone who is interested in achieving top accuracy from his pistol will be using the powder which meters with lower SD and max spread. However even the great powders like N310, W231, AA2 meters with deviations.
I compared some popular loads for .45 ACP with .40 and 9mm load with same deviation to see the pressure differences with same powder measure deviation.
For example .45 Nosler 185 JHP, OAL 1.200, 4,1 gr N310 in 4" barrel - pressure 15405 vs 15800 with 4,16 gr - 8 fps difference. In .40 the same deviation of only +-0.015 gr and the difference in pressure is 495 psi and 9 fps. In 9x19 it si 848 psi and 10 fps. Deviation of 0.015 gr is very small. I suppose that many reloaders get +-0.05 gr. With this deviation it is 649 psi (.45) vs. 829 psi (.40) vs. 1421 psi (9mm). And the same thing goes with the OAL - 0.01" change changes pressure for 436 psi (.45) vs. 497 psi (.40) vs. 912 psi (9mm).
These deviations in bullet seating and powder measuring can be limited but not eliminated. The absolute pressure difference will be always bigger in smaller cartridge. How important is this in terms of accuracy? When we consider the shape of the bullet, the 9 mm is much better than the .40 or .45. At least in terms of Miller twist rate rule. The ratio between the length and diameter of the bullet will be always better in 9 mm bullets.
Let's have 1911 with 3 different barrels, all fitted properly by gunsmith. Which caliber has the biggest potential when the accuracy is all that matters (we don't mind low power factor nor the gun recoil of kicking horse)?

 

[fxvr5]

Gunsmiths who build custom 1911s for bullseye generally give the nod to 9mm and 38 Super for better accuracy over the 45.

https://chamberscustom.com/about-us/

"His 1911 style pistols in .45acp shoot 10 shot groups at 50 yards between 1.100” and 1.500”, with the average of 1.350”. The guns built in 9mm and .38 Super average just under 1.00” for 10 shots at 50 yards."

40 S&W does not appear to be a caliber used for bullseye shooting, so there's little data for it.



Extreme spread in velocity does not appear to be positively correlated with smaller groups, at least not with a typical handgun at 25 yards, so selecting a powder that produces a small deviation in velocity does not guarantee smaller groups.

https://americanhandgunner.com/handguns/exclusive-consistent-velocity-accuracy/


Are you measuring pressure or estimating it with software?

 

[tfk]

Well, that's really interesting. So many guys swore by 1911 and .45 ACP... I am only estimating pressure - calculating with QuickLoad. And I know that small deviation in velocity does not mean that the group will be smaller. The ballistic coefficient is mainly topic related to rifles, but 145 gr HP bullet of .356" diameter has better BC than .45 ACP, also the 9mm has flatter ballistic curve than .45 ACP. It seems that when one has a properly fitted gun, then the bullet and its shape is more important than a slightly bigger deviations in pressure. The info about 38 Super is very interesting. I didn't think about this cartridge at all. It is very good combo. Bullet almost identical to 9mm and the larger case and therefore less deviation than in 9mm. Thank you very much.

 

[Jonesy814]

What happens to 45acp accuracy potential if the bullet is a 200gr semi wadcutter?

 

[JeeperCreeper]

.45 makes bigger holes. More chance to hit the bullseye.

 

[fxvr5]

What happens to 45acp accuracy potential if the bullet is a 200gr semi wadcutter?

My understanding, based on what bullseye shooters say, is that jacketed bullets are more accurate than lead bullets.

So, if you're going from the best jacketed loads to the best lead loads, accuracy gets worse.

 

[tfk]

What about .357 Sig or 9x25 Dillon? Is there any benefit in accuracy compared to regular 9x19?

 

[saiga308]

round nose 40 cal bullets should do better than the original flat types at longer range.


https://www.lutureammo.com/products/custom-reloaded-handgun-ammunition-40-cal-s-w-40x180-gr-50-rds

 

[tfk]

Can you explain why. My experience from 9mm is rather opposite.

 

[ATLDave]

I am extremely skeptical that there is any such thing as an "inherently accurate" cartridge configurations when it comes to handgun cartridges and handgun distances, much less any kind of inherent cartridge advantage that is so significant it can be detected amidst all the other variables.

 

[Bfh_auto]

.45 makes bigger holes. More chance to hit the bullseye.

I was thinking the same thing. Easier to touch bullet holes.

 

[fxvr5]

round nose View attachment 862843 40 cal bullets should do better than the original flat types at longer range.

https://www.lutureammo.com/products/custom-reloaded-handgun-ammunition-40-cal-s-w-40x180-gr-50-rds

In general, flat nose bullets, such as flat point, hollow point, wadcutter and semi-wadcutter bullets, produce smaller groups than round nose bullets. That was statistically compared in this article:

https://www.ssusa.org/articles/2019/1/18/38-different-9mm-loads

Most competitors, especially bullseye shooters, use flat nose bullets, especially hollow point bullets, when bullet design is not limited by the rules.

 

[fxvr5]

What about .357 Sig or 9x25 Dillon? Is there any benefit in accuracy compared to regular 9x19?

There's probably not enough data with .357 Sig and 9x25 Dillon for a meaningful comparison with the 9mm. The thing about bullseye guns in 9mm, 38 Super and 45 ACP is that there are lots of them being made and tested by excellent gunsmiths with the correct methods (Ransom Rest or barrel fixture), so there is a large data base with the quality data required to make that type of comparison between 9mm, 38 Super and 45 ACP calibers.

 

[fxvr5]

.45 makes bigger holes. More chance to hit the bullseye.

If the 45 and 9mm shoot the same group size, then, yes, the 45 will be more likely to hit the higher scoring ring because the 45 bullet is fatter.

If the 45 is less accurate than the 9mm, it can be no more than 0.096" less accurate (the difference in diameter of .451" and .355" bullets).

Using the numbers in post #2: the average 45 group is 1.350" and the 9mm is under an inch, let's round up to 1.00". That's a difference of 0.350". That exceeds the 0.096" difference in bullet diameters, therefore the 45 is not more likely to hit the higher scoring ring. This means the 9mm (and 38 Super) have a measurable edge in accuracy and are more likely to produce a higher score.

 

[ATLDave]

If the 45 and 9mm shoot the same group size, then, yes, the 45 will be more likely to hit the higher scoring ring because the 45 bullet is fatter.

As I understand it, this is why the 6mm projectiles are the king in the benchrest 100 and 200 yard group shooting competitions, while the guys shooting score competitions use fatter bullets.

But I'm definitely not a rifle benchrest guy, so I'm just repeating what I have read/been told.

 

[GW Staar]

This is a curious thread....interesting but still curious ....times and attitudes change....

I went back and got out some old "Jeff Cooper" articles, to see why he was such a fan of .45 acps. I found this old quote:

“The 1911 pistol remains the service pistol of choice in the eyes of those who understand the problem. Back when we audited the FBI academy in 1947, I was told that I ought not to use my pistol in their training program because it was not fair. Maybe the first thing one should demand of his sidearm is that it be unfair.” — Col. Jeff Cooper, GUNS & AMMO, January 2002

Anyone know why his 1911 chambered in .45ACP would be considered "not fair"? And how the 9mm has suddenly gotten so superior to it?........I seriously doubt the size of the holes was the reason they cried "unfair". Size of a wound....maybe.

Another thought.......a 1" group is a 1" group, caliber unspecific if you measure center to center.

Did Jeff think the .45 caliber was superior due to its extreme killability? or accuracy? I don't have that answer. His favorite caliber for self defense was 30-06, but he couldn't carry that on his belt.

 

[Jim Watson]

I went back and got out some old "Jeff Cooper" articles, to see why he was such a fan of .45 acps. I found this old quote:

“The 1911 pistol remains the service pistol of choice in the eyes of those who understand the problem. Back when we audited the FBI academy in 1947, I was told that I ought not to use my pistol in their training program because it was not fair. Maybe the first thing one should demand of his sidearm is that it be unfair.” — Col. Jeff Cooper, GUNS & AMMO, January 2002

Anyone know why his 1911 chambered in .45ACP would be considered "not fair"? And how the 9mm has suddenly gotten so superior to it?........I seriously doubt the size of the holes was the reason they cried "unfair". Size of a wound....maybe.

Another thought.......a 1" group is a 1" group, caliber unspecific if you measure center to center.

Did Jeff think the .45 caliber was superior due to its extreme killability? or accuracy? I don't have that answer. His favorite caliber for self defense was 30-06, but he couldn't carry that on his belt.

Seven shots instead of six.
Quick reloading. (They wanted him to use one magazine and reload it with loose rounds to offset that unfair advantage.)
Single action trigger pull "automatically."

Pistols aren't shot for group, if you touch the line, it counts. I typically gain about two points in an IDPA match with the bigger holes. One day, six.

In the pre-Super Vel era, a bigger bullet was the route to "stopping power."

 

[Swampman]

This may be being "overthunk".

It'll be a very happy day when I can achieve 50% of the accuracy my pistols and ammo are actually capable of.

 

[GW Staar]

Seven shots instead of six.
Quick reloading. (They wanted him to use one magazine and reload it with loose rounds to offset that unfair advantage.)
Single action trigger pull "automatically."

Probably right, there.....forgot they were stuck with wheel guns then. On the street, an agent would want an unfair advantage, as he pointed out.

Pistols aren't shot for group, if you touch the line, it counts. I typically gain about two points in an IDPA match with the bigger holes. One day, six.
On the range then, another "unfair" advantage! Seems to me a smart advantage.
In the pre-Super Vel era, a bigger bullet was the route to "stopping power."

bigger bullet, more stopping power? still is, all other things equal...... If I could shoot one without pain, a .50 cal or bigger .... even better.....

But this thread was about accuracy....

I once had a Colt Gold Cup (what a sweet shooting pistol! and the slide was twice as light as any .45 I've had since).....I sold it because I didn't want to wear out a collectors gun....I was into shooting, not collecting. Replaced it with a Kimber target .45. (Much tougher slide to rack) Both are accurate as far as pistols go....but the most accurate pistol is the one you can shoot most accurately........for me that turned out to be a Ruger SR40 (.40S&W). That thing kicks like a 9mm, has a few more in the magazine than the Kimber, and is just as accurate......so that's what I carry......heck with the nay sayers. (and it's Ruger Reliable....if you have good ammo you have zero feeding problems....no break-in was required.)

 

[Walkalong]

Another thought.......a 1" group is a 1" group, caliber unspecific if you measure center to center.

Yep, center to center to measure groups.

 

[Jim Watson]

But scores are to the edge of the hole. Unless you shoot NMLRA where there are so many different calibers of muzzleloader in use that they plot the centers.

We have a gunsmith's numbers that indicate the smaller calibers should be enough more accurate to offset the .45 holes.
But from what I read, many to most NRA shooters shoot a .45 in Centerfire where they could have one of those mediums. Or even a smallbore. Where are those ISU .32s at Camp Perry?

 

[Walkalong]

But scores are to the edge of the hole.

Yes, it pays to have a bigger hole in score shooting vs group shooting, makes no difference in group shooting.

 

[murf]

But scores are to the edge of the hole. Unless you shoot NMLRA where there are so many different calibers of muzzleloader in use that they plot the centers.

We have a gunsmith's numbers that indicate the smaller calibers should be enough more accurate to offset the .45 holes.
But from what I read, many to most NRA shooters shoot a .45 in Centerfire where they could have one of those mediums. Or even a smallbore. Where are those ISU .32s at Camp Perry?

easier to learn to shoot two guns rather than three. I think that is the reason for a lot of shooters.

murf

 

[Jim Watson]

Cheaper, too.

 

[ATLDave]

Cheaper, too.

Yeah. I'd guess this is probably more significant than many people think. If you're shooting bullseye at a high level, you're probably shooting at least a heavily-smithed gun, if not a quasi- or full-custom. There's a lot of money in dedicated competition gear in my pistol shooting sport (USPSA), and I don't think it's less in bullseye where tiny tolerances are the norm.

If you've got $3k to spend to cover all the centerfire gun requirements, you might be best off sinking that all into a well-tuned 1911 in 45 and just shoot it in both the 45-required and any-centerfire portions of the match, rather than buying a $1.5k 45 1911 and a $1.5k [other gun in non-45].

But I'm not a bullseye shooter, so I could be missing the calculation.