Overpressure vs Speed

[turq]

There is a warning in Nosler #6 book about Mil. cases making more pressure.

That primer is flat but not overly flattened.

Look at the pressure levels of W748 in the Hodgon's 2010 annual manual.
Only list is a max(?) 26.3=3150fps producing 39,000CUP ***
Max for BL-C(2) is 27.5=3313 at 48,500CUP
Min. for BL-C(2) is 25.5=3069 at 37,200CUP
So if you use a min. load with these powders (the BL-C(2) you were using)it should be giving you a speed near 3000fps.
Was that too many numbers? This is how I determine my reloading powder with a chosen Bullet weight.
Might give the 748 a try for less pressure sign.???

 

[Gunner3456]

There is a warning in Nosler #6 book about Mil. cases making more pressure.
-snip-

Good point. We've discussed that in other threads. The Mil cases have thicker brass and therefore a smaller volume inside. That's what causes the pressure to build faster and higher. You do have to work up different loads for that, and again I preach the use of a chrony. I work up to factory Mil spec speeds while checking the cases for pressure signs.

 

[CrossHairs]

Yes, I was aware of the mil case thickness difference and was trying to factor that into the equation. I think I have this covered now as it does seem that the primer issue is partly due to the rifle it's fired from as well as the primer itself. I'm happy that the loads are not too hot as they fell into the lower range in most cases.

I'll keep an eye on things but the chrony and the loads tell me that everything should be under control.... For now!

 

[Gunner3456]

The things that most make a 5.56 AR worthwhile and deadly is it's bullet speed, flat trajectory, and tendency to tumble on impact. At speed, on impact, the bullet is likely to tumble and break up. It can cause wounds which are far worse than one might think just looking at bullet size.

For plinking, who cares unless you're reaching out several hundred yards. For all-around self defense, I want 3150 fps from a 55gr. The gun and the ammo are built for those pressures if chambered for 5.56 and not just .223.

$.02

 

[gnarl]

I immediately suspected that the primers are a little softer than factory ammo because I also threw in a few loads that had gone through the Savage, and they too appeared to have a little flattening, yet I did not notice that when I fired them from the savage.

Thoughts? Warnings of dire consequences?

Just take a box of new CCI primers, use a torch to bring them to dull red heat,
then quench them in ice water; should be considerably hardened.

Er...actually, you probably shouldn't do this.

 

[AMProducts]

Brass does not harden by application of heat, it only hardens through cold working. This is why annealing (heating) brass softens it.

After digging through this thread it looks like you're on the right track, interestingly I never had any luck with IMR4198 even cycling my .223 back in the day.

However, I will tell you this, when you spend time developing loads, for every powder there is a "happy zone" where SD and ES will suddenly drop into single (or nearly) digits. As you move up, things will get radically worse, and as you move down things will get steadily worse. Certain powders like the IMR type powders have a larger happy zone than ball powders. Also, once you get to the upper end of this happy zone you will start seeing very erratic pressure swings as well, while the average shooter might not notice this, I definitely do when I look at the transducer output.

 

[CrossHairs]

Looks like a little thread resurrection!

I should have updated the thread I guess. Anyways, I did find some mil spec primers and guess what...similar results. Bottom line, the Colt has a very hard strike.

gnarl - Yeah, maybe I should try that trick....it might wake the neighbours though!