why the low pressure limits on .45 acp?

[4570]

Why the low pressure limits on .45 acp compared to other calibers?

I am asking cause I have bought a S+W 625-2, a STI ranger 2 and some starline +P brass.

Yes I do plan on reloading within specs.

Is it the old 1911's being weak?

The old brass that is still reloaded may be weak?

Or the 45 case itself?

[G-ManBart]

The 45acp is a hundred years old and smokeless powder was still pretty new then. You'll find similarly low pressures with other cartridges from the same era. The worry is that if they make ammo to the pressures that a current manufactured 1911 and brass can handle it could wind up in a gun that's nearly a hundred years old and bad things could happen

If you go over the pressure that the brass can handle with an unsupported chamber about all you'll do is blow the grips to pieces and send the mag flying out the bottom...problem is when you get the grip pieces in your hands!

[Chris Keen]

'tis but a flesh wound!

[Carlos]

Why the low pressure limits on .45 acp compared to other calibers?

I am asking cause I have bought a S+W 625-2, a STI ranger 2 and some starline +P brass.

Yes I do plan on reloading within specs.

Is it the old 1911's being weak?

The old brass that is still reloaded may be weak?

Or the 45 case itself?

1911 barrel = ZERO CASE SUPPORT AKA UNSUPPORTED CHAMBER. The 1911 has always had an unsupported chamber. Only exceptions are the 1911s modified for use with ramped barrels - like USPSA's STI and SV guns (technically, "2011"). Since .45 ACP is limited to such low pressure, it creates no issues.

HOWEVER, you mentioned you shoot a 625 revolver. It has FULL case support. Opinions vary, but most agree the 625 can handle ".45 Super" with no modifications. Do a search on 45 Super for data and precautions. With good brass and full case support like your 625 offers, the basic .45 case can handle higher pressures than the loading manuals would lead you to believe.

[bigsaxdog]

the pressure has got to do with the volume of the case, powder capacity, etc. check out some of the larger rifle calibers, 45-70, .375H&H, the big african nitro-express', etc. there is some correlation between the volume of gas created by the greater volume of the cases....gets the velocity from less pressure, but still plenty of gas....there is design involved in the case/pressure thing, JMB knew what he was doing. on the other hand, alot of people stating reload data all over the internet don't know there rear ends from their elbows, so the moral of this diatribe is to DO YOUR HOMEWORK....i'm really not going off half cocked, i'm just amazed at some of the reloading stuff i read on the computer, and the lack of fear for the possible results.....

[Run n Gun]

Though kind of a round-about way to get to it, >THIS< article about the 45 Super ® should answer a lot of your questions...

Ed