Unicorn Primers

[Nick_C_S]

Went to the range today. Did some chronographing and whatnot.

I also bolt-locked chambered a round, and then took a look at the primer. Sure enough, it had a little kiss on it. Pretty tiny, I'd say. I can't imagine a tap that small ever detonating a primer. But hey, I'm no expert.

I've had light primer strikes with my race revolver that were much more extensive.

[Metal god]

Well what were your results ? Did the crimp tighten up your ES/SD

[Nick_C_S]

From earlier (for context):

Metal god: Thanks for the advice on the crimp. So far, I've only tested 5 rounds and my SD was 118 (only a 5-round sample, but still). They were not crimped. Sierra 65 SBT; 24.0gn AA2230.

I have since loaded 5 rounds each at 24.0 and 24.2 grains. I gave these a slight collet crimp. And yes, my reason for crimping was due to the 118 SD. My goal is to just get this bullet shooting accurately at 50 yards (using AA2230) and to have proper feeding/cycling. I'm not asking much.

From Metal god:

Well what were your results ? Did the crimp tighten up your ES/SD

Sierra 65gn SBT; AA2230; #41 primer.
24.0gn 2822 f/s; 22.26 SD
24.2gn 2846 f/s; 38.28 SD

Again, small sample size. But the crimp does appear to have soothed the SD.

Now that I'm "in the ballpark," I'm going to load 10 rounds each at 24.0; 24.2; and 24.4 grains. We'll see how that goes. Yes, I'll give 'em a collet crimp; that's pretty much a given at this point.

[Metal god]

Cool , looking forward to your next results

[Nick_C_S]

Cool , looking forward to your next results.

I have the "next results."

This time, it is 10 round samples. To recap, for those not keeping score at home:

Sierra 65gn SBT #1395. AA2230 propellant. CCI #41 primers. "LC 16" cases; trimmed to 1.75" 2.245" OAL. Medium collet crimp. AR-platform rifle; 16" bbl, 1:7 twist.

All of the following charge weights are in compliance with Sierra Edition V, 65th printing load manual.

24.0gn: 2809 f/s; 189 ES; 51.53 SD
24.2gn: 2842 f/s; 97 ES; 35.65 SD
24.4gn: 2827 f/s; 158 ES; 52.05 SD

This time, the crimp did no good, so it would seem. The primers are looking slightly flattened and so I am not going to push this work up any farther. The purpose of this load workup is to have some ammo to store for any future need - reliability is the primary requirement. If I wish to load this bullet/propellant combination for maximum consistency, I'll go with CCI 450 primers - they seem to deliver more consistent results. I'm setting the charge weight at 24.0 and calling it good.