1911Forum banner

1 - 10 of 10 Posts

·
Registered
Joined
·
13 Posts
Discussion Starter #1
Howdy all, I've been loading for all rifle types and revolvers for 25 yrs now. I'm fairly new to the auto pistol scene, I've got a USP and just bought a Kimber .45. Are pressure signs similar with the autos? I mean do I look for flattened or cratered primers as in other autos? No sticky bolt to turn or sticky case to eject from a cylinder. What other pressure signs to I look for? I just loaded up some Precision 230 gr. lead RN over 4.8 and 5.0 grains of Titegroup and a fed. LP primer. I averaged 880 fps with the 4.8 load and 950 fps with the 5.0 load out of the Kimber, a little slower with the shorter tubed HK. No Pressure signs, but 950 seems a little fast for the 230 gr. even though it's a "coated" bullet. TIA, Gary
 

·
Banned
Joined
·
14,948 Posts
Pressure signs in .45ACP are not always easily detectable. The cartridge itself is a relatively low-pressure round, compared to .40 S&W or 9mm or .38spl, so it is somewhat forgiving with regard to pressure.

I would simply pay more attention to your reloading manuals, (consult several)and stay within the guidelines. If your gun is sound, and you are using quality brass in good shape, then you will be fine, even when approaching max. loads.

There is not much improvement in velocity and usually diminishing accuracy as you start pushing the envelope of a given load. The .45ACP cartridge is not designed for warp speed. Best results are usually found with a mid to mid-high loading as far as accuracy and velocity.
 

·
Registered
Joined
·
550 Posts
The weak point in the system is the feed ramp area of the barrel where the case head is not supported. The typical .45 failure mode is a case failure at this point, which usually blows out the magazine and sometimes blows the grip panels off. As pressure approaches this level, you may see a bulge in fired cases that is not concentric and fits into the feed ramp. At this point, pressure is way too high.

Prior to that level of pressure, the primer is usually the only visible indication of overpressure. Primer flattening and breech face marks on the primer will be in evidence, but it is difficult at this pressure level to read them.

A modern .45 barrel will usually take pressure well over SAAMI specifications for the .45, so any load recommended in a reliable manual should be fine. However, if you go beyond the recommended level, it is difficult to read pressure and the first non-subtle indication of a problem could be case failure. It is best to stay with published loads with this cartridge.
 

·
Registered
Joined
·
605 Posts
The problem with using primer as indicator of excessive pressure is that by the the primer shows signs of excessive pressure the actual pressure maybe way over the SAAMI specifications. 45ACP is a low pressure round so "standard" pressure loads will not leave noticable marks/signs on the primer. I use a chronograph to check my loads and start backing off when the velocity is higher than "normal". Same with case expansion method.

Personally I don't push my loads beyond following velocities:

180-185gr bullets - 1,050fps
200-210gr bullets - 1,000fps
230gr - 900fps
250gr - 850fps


Just my $0.02
 

·
Registered
Joined
·
688 Posts
The typical .45 failure mode is a case failure at this point, which usually blows out the magazine and sometimes blows the grip panels off.
I know guys who use steel plates under the grips to protect their hands. I still have a set. Just have to move the feet fast enough to avoid the mag. LOL

Eddie
 

·
Registered
Joined
·
2,845 Posts
The pachmyer grips with their steel inserts always made me feel safer back in my early .38 Super days with the old style barrels that headspaced on the semi-rim. Back then I used to push the envelope and blew out more than one case. Not a very pleasant experience.

Personally I feel that felt recoil is not a perfect indicator, but it's something else to add to the "toolbox".
 

·
Registered
Joined
·
13 Posts
Discussion Starter #7
Howdy all, well I just bought the new Hornady Reloading manual and guess what? They have a max load with 230 grain lead at 900 fps with 5.3 grains of titegroup. The max loads with 230 gr. Jacketed pills is listd as 5.2 grs. Made me feel better since I'm not seeing any signs of pressure with the 5.0 loads. Remember I told you that I'm getting 950 fps! I told you that these Precision Bullets were slick and fast!
 

·
Registered
Joined
·
550 Posts
Clark, interesting experiments.

How did you measure pressure?

At what point did you measure web thickness, and how did you determine that point?

Is the web thickness required for a certain pressure level different in different cartridges, or is it a linear relationship?

Thanks. Very interesting data.
 

·
Registered
Joined
·
171 Posts
Amazing and interesting! Would have loved to have seen some of those experiments. We have a safety margin guy here, also.
 
1 - 10 of 10 Posts
Top