9mm reload crimp measurements

[M27]

weight is not an absolute, but I will check that out with my calipers later

[Bill Steele]

Not in 9mm. RP is on the thick side. Weigh the brass.

I have actually never paid attention to 9mm cases. I have always sorted my 45 Auto where the R-P brass is decidedly thinner and where I care most about it as that is where I load the most lead.

So I did totally scientific scoop of the hands in the bucket of 9mm brass sampling. I deprimed the brass and the weight results were definitely different than I would have expected versus my experience with R-P (and other headstamps) in 45 Auto.

The R-P were still on the light side of the various headstamps I scooped. The CBC (Magtech) was heavy, just like it is in 45 Auto. The Blazer brass also heavy, the FC (from I suspect their blasting ammo line was also very heavy). The heaviest cases weighed were WCC (NATO) brass.

The really interesting result was PMC, R-P, S&B and Win were all within a few tenths of a grain of each other (multiple were weighed in each headstamp) and decidedly lighter than the foregoing.

Another interesting result was the FC headstamp with cases that I assume were from their premium line as they had a mid-case cannlure, were by far the lightest of any I weighed (so I have a new favorite if I load some lead in 9mm in the future).

As M27 noted, weight is not the definitive factor as web thickness, primer cup architecture (the R-P brass has a big old chamfer cut around their primer pocket, just like in 45 Auto) has to have an fairly major impact on overall case weight versus the thickness of the brass.

I will try and find that ball end micrometer and do some measuring to get some definitive conclusions. In general, I think R-P, Win and PMC will still be my go to cases for lead and 9mm, when I don't have enough of that special cannelured FC stuff. For jacketed, Blazer, Magtech, run of the mill FC and NATO brass will be my jacketed fav's, if the ball end micrometer bears out the weight test results, that is.

Some fun.

[CGT80]

9mm is listed as 1.169" max COAL if I recall correctly. Some bullets that I use for my mom's XD 9mm factory barrel have to be 1.115" with a 124 grain bullet. I run a barsto barrel in my competition XD, but I had the throat tapered deep enough to run my preferred bullet, and the chamber had to be finish reamed beyond what was done when barsto made the barrel. Now the magazine is my limiting factor since I run 40 cal mags (40 cal gun) for my 9mm ammo in this gun. Seating depth changes with the bullet and gun I load for.

I found I was crimping too much when using moly coated lead bullets. I set my crimp so that when a pull a crimped bullet, you can just see a line from the case mouth, but you can't feel it. This took my standard deviation in fps from 20-30fps or more to 6-8 fps over a string of 11 rounds with an average velocity of just over 1,000 fps. That is the same consistency as jacketed factory ammo in the same barrel.

I also use my fingers as a guide for crimp. The case should feel straight, without any flare at the mouth. The plunk test into the barrel works with all bullets I have used, except the moly coated lead bear creek in 9mm. They hand up just ever so slightly, but they run fine. I also can't use a case gauge to check those loaded rounds as it hangs up as well. All other bullet worked with a case gauge. It comes down to trial and error while being as careful and observant as possible when you work up a round for each gun.