45acp +P 275gn pressure test

[lar45]

Hi everybody, I've been loading the Hunter's Supply 45-275 in my 45 Colt and 45acp for awhile now and asked Larry Gibson if you would pressure test the ACP loads just to see where they were at.
I boxed up some primed brass, bullets and load data along with some money for powder and shipped it off.
Larry assembled them and ran them through his pressure barrel.
Quickload estimate:
45acp-275, seated to 1.237" in Rem brass with Win LP primers, BlueDot, 7" barrel.
8.7gn - 1035fps, 24kpsi 114% compressed load
9.0gn - 1046fps, 27kpsi 118%

Larry's findings:
Testing was done in a Contender 10" 45 ACP barrel. Ambient temp was 75 degrees with a 15% humidity. All rounds were loaded as per your specifications.

The 8.7 gr Blue Dot load under the 45-275 bullet ran 1047 fps with an ES/SD of 74/20 fps. The psi averaged 24,000 with an ES/SD of 7,800/2,300 psi.

The 9.0 gr Blue Dot load under the same bullet ran 1110 fps with an ES/SD of 76/23 fps. The psi averaged 27,300 with an ES/SD of 5,600/2,100 psi.

Nothing abnormal was observed in the pressure traces of either load.

So it looks like the 8.7gn load should be safe for 45ACP+P and the 9.0gn load should be safe for 45Super.
I thought it was very interesting that the Quickload predicted pressures were very close to the actual measured pressures.
Larry's velocities were higher than mine, but he used a 10" Contender and my gun is a 7" AMT LongSlide HardBaller.
Larry also cautioned that a heavy recoil spring and shock buff be used and to watch for excessive slide velocity, also use sparingly so as to not batter your gun.

I have a heavier spring in my 7" LongSlide and the empties just tumble out at my feet. So I'm assuming that they are safe in my LongSlide, but I don't think I'll shoot them in the Star PD with it's 3.5" barrel and Aluminum frame.

[Electrod47]

Somebody was wanting a "Bear Load" on here recently for a 45acp 1911. I guess this is it.

[ranchman]

What were your velocities chronographed at vs what Larry's data showed through the long contender barrel?

[lar45]

From my 7" Longslide vs 10" contender
8.7gn load was 1035fps vs 1047
9.0gn load was 1046fps vs 1110

[Kosh75287]

Hi everybody, I've been loading the Hunter's Supply 45-275 in my 45 Colt and 45acp for awhile now and asked Larry Gibson if you would pressure test the ACP loads just to see where they were at. I boxed up some primed brass, bullets and load data along with some money for powder and shipped it off. Larry assembled them and ran them through his pressure barrel.
Quickload estimate:
45acp-275, seated to 1.237" in Rem brass with Win LP primers, BlueDot, 7" barrel.
8.7gn - 1035fps, 24kpsi 114% compressed load 9.0gn - 1046fps, 27kpsi 118%

Larry's findings:
Testing was done in a Contender 10" 45 ACP barrel. Ambient temp was 75 degrees with a 15% humidity. All rounds were loaded as per your specifications.
The 8.7 gr Blue Dot load under the 45-275 bullet ran 1047 fps with an ES/SD of 74/20 fps. The psi averaged 24,000 with an ES/SD of 7,800/2,300 psi. The 9.0 gr Blue Dot load under the same bullet ran 1110 fps with an ES/SD of 76/23 fps. The psi averaged 27,300 with an ES/SD of 5,600/2,100 psi. Nothing abnormal was observed in the pressure traces of either load.
So it looks like the 8.7gn load should be safe for 45ACP+P and the 9.0gn load should be safe for .45 Super. I thought it was very interesting that the Quickload predicted pressures were very close to the actual measured pressures.
Larry's velocities were higher than mine, but he used a 10" Contender and my gun is a 7" AMT LongSlide HardBaller. Larry also cautioned that a heavy recoil spring and shock buff be used and to watch for excessive slide velocity, also use sparingly so as to not batter your gun.

I have a heavier spring in my 7" LongSlide and the empties just tumble out at my feet. So I'm assuming that they are safe in my LongSlide, but I don't think I'll shoot them in the Star PD with it's 3.5" barrel and Aluminum frame.

For such loads, a heavier mainspring coupled with a flat-based (unradiused) firing pin stop would probably not be a waste. It might also be worth an E-mail to the Rowland folks to see if a semi-custom version of their .460 Rowland conversion might be fitted to the long-slide. If not, then perhaps their 5" barreled kit would achieve somewhat the same thing?

[ddixie884]

Good info thanx for sharing...........

Larry is a heck of a guy..........

[Bigslug]

For such loads, a heavier mainspring coupled with a flat-based (unradiused) firing pin stop would probably not be a waste.

+1.

[DougGuy]

Afaik, 45ACP+P pressure is 23kpsi not 24kpsi.

[GLynn41]

seems that in long run that load would be hard on a 1911.. Interesting

[45 Dragoon]

Nice for single action revolvers though!!
Thanks!!

Mike

[DanOH]

Are there any issues with case bulges with that length boolit or is the extra lead all in the ogive exterior of the case?

[lar45]

No bulging of the cases.