Why is the .45 ACP more accurate than other duty calibers?

[Little Creek]

SLG mentioned this in another thread, and instead of cluttering that up I figured I'd ask here. It jives with my own experience, but I just chalked it up to shooting single stack better or the general awesomeness of the 1911 and Sig P220.

So, why is the .45 ACP more inherently accurate than .40 S&W?

Where is the proof?

[SLG]

Where is the proof?

Same here. Did you read the thread?

[Little Creek]

Same here. Did you read the thread?

Have a nice day!

[Velo Dog]

From Winchester's law enforcement ammunition webpage, one can select a specific load then view the factory spec sheet which includes the "Product Mean of___inches (__cm) Extreme Spread 5 shot targets at 50 yards (45.7m)" from 4 or 5 inch SAAMI test barrels.
http://winchesterle.com/Products/han...s/default.aspx
The best 9mm Luger loads have a product mean of 1.25"
http://winchesterle.com/Lists%2FCata...13%2FRA9TA.pdf
The best 45 Automatic loads have a product mean of 1.50"
http://winchesterle.com/Lists%2FCata...1%2FRA45TP.PDF
The best 40 S&W loads have a product mean of 2.00"
http://winchesterle.com/Lists%2FCata...0%2FRA40TA.pdf

Note that the 45 Automatic +P had the same accuracy as the standard pressure loading.

The 165gr. 40 S&W had the same accuracy as the 180gr. loading.

The 9mm Luger achieved a product mean of 1.25" with 3 different bullet weights and 3 different pressure levels.
http://winchesterle.com/Lists%2FCata...2FUSA9JHP2.pdf

[Jim Watson]

One factor I can think of is that there is no incentive to make very accurate .40 guns and ammo.

Take a .40 to a NRA bullseye match and it will be a Centerfire competing with thoroughly developed .38s and .45s.
Take a .40 to a CMP EIC match and it can probably compete in the recently much enlarged Service Pistol category versus well developed 9mms and .45s.
So why bother? It is so much easier just to go with something that already works well.
And you can't shoot it at ISSF(ISU) at all.

No others need apply.
Accuracy requirements for USPSA are much less, not hard to come up with an acceptable combination but that is not the same as the X Ring at 50 yards.

[Velo Dog]

The U.S. Army Marksmanship Unit at Ft. Benning, Georgia, knows how accurate the 9x19mm can be.
“We’re getting all of our guns to generally shoot less than 1-1⁄2 inches at 50 yards for a 10-shot group (with the competition rounds)”
http://www.handgunsmag.com/reviews/f...gnedm9_200809/