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1/25/2018 7:38:29 AM
Posted: 12/10/2001 3:34:19 PM EST
how much velocity do you lose coming from a 5'' barrel 1911 down to my 3.8'' USP compact. dont get me wrong, i dont feel "undergunned" by any means, just wonderin


Link Posted: 12/10/2001 3:52:11 PM EST
I have heard between 30 and 100 fps per inch,,,,depending on powder and bullet
Link Posted: 12/10/2001 5:34:35 PM EST
Almost impossible to estimate. Best bet is to chrony the rounds. I get 876FPS out of my 1911 5" loading 200gr LSWC on top of 4.8gr of Titegroup.
Link Posted: 12/10/2001 6:50:09 PM EST
I lose about 10 fps between my Kimber 5" and HK compact shooting 230 fmj. Possibly the polygonal rifling lives up to claims of higher velocity per unit of barrel?
Link Posted: 12/10/2001 6:51:14 PM EST
P.S. I don't know if my pact model 1 chrono is smart enough to really quantify that difference of 10fps anyway. Don't worry!
Link Posted: 12/10/2001 7:54:08 PM EST
Check out this page www.greent.com/40Page/index2.htm

It has a good info on a wide range of pistol calibers. The fourth link under 45 on the left side should be what you are looking for though.It has the difference between velocities of different loads shot from a glock 21 (4.6") and a glock 30 (3.78")

Link Posted: 12/10/2001 9:41:39 PM EST
There was an article in a gun magazine (and I don't recall which one or date) that compared barrel velocity for about five 1911 barrels ranging from officer to fullsize length.

Velocities were all over the place, apparent correlation between velocity and barrel length.

Maybe the polygonal USP barrels are sufficiently tightly manufactured that a consistent reduction in velocity between the compact and fullsize would be apparent.

But the guys who say that you should chrono your pistol are right.
Link Posted: 12/11/2001 4:52:16 AM EST
I chronographed 230gr ammunition that shoots 850 fps from a standard 5.25" M1911 barrel at 840-845 fps from the USP 45 Compact. Not enough drop in velocity to be statistically significant.

I suspect the polygonal rifling forms a much tighter gas seal.

-- Chuck
Link Posted: 12/11/2001 5:24:09 AM EST
Using Federal +P ammo in my 4" Kimber I get 950 FPS. 5" guns get 1050. Yes, a shorter barrel will give less velocity. (Hush, I don't think anyone getting hit by a .45 will know the difference)
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