Primer selection for 5.56 pressures

diananike

diananike

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Howdy
I just bought a 5.56 Ruger Scout. It's a 1:8 twist so is suitable for the heavier 75 and 77 grain bullets so I'm leaning towards the heavier bullets and the terminal ballistics that come with them.
Issue is it has a 16" barrel so I'd like to max out the range available out of this combination for hunting deer.
On order to get effective range out of this rifle with heavy bullets I'd like to load it to 5.56 pressure levels.
Having had some pierced primers with heavy loads with regular small rifle primers I'm thinking I might need to switch to milspec or Magnum primers with the thicker cup.

Do you guys think switching to milspec or Magnum primers would mitigate these pierced primer issues?

Any input and experience would be appreciated.
Thanks a bunch
Sam
 
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I've only ever used standard rifle primer's. If your piercing them it sound's like a firing pin issue, or your getting on the hot side
 
Definitely hot loads. I'm loading up to 5.56 pressures. They tend to pierce on hot summer days. If I'm shooting at cooler temps it's not a problem.

Maybe I'll try the CCI br4 if they have thicker cups.
 
It is recommended to use primers with a cup thickness of .025 with the .223/5.56.

calhoonprimers02.png


If you are bumping the case shoulder back too far it allows the primer to back out of the primer pocket excessively. And when the chamber pressure increases the base of the case stretches to meet the bolt face. And this can cause the firing pin to punch a hole in the primer just like a cookie cutter.

piercedprimer-CCI400-1.jpg


If the primer looks like below there is excessive clearance around the firing pin and the primer can flow around the firing pin.

piercedprimer-CCI400-72.jpg


Check the tip of your firing pin to see if it has been damaged by high pressure gas leakage.

CHOOSING THE RIGHT PRIMER - A PRIMER ON PRIMERS
http://www.sksboards.com/smf/?topic=56422.0

Bottom line, I load for three AR15 rifles and a bolt action Savage .223 and only use the thicker cup .025 small rifle primers and never have a problem.

NOTE, max pressure for the .223 is 55,000 psi and now the newer 5.56 M855 ammo is loaded to 58,700 psi. So if you are going to load hot you need military cases like Lake City that are made of harder brass.
 
jethunter said:
Whether heavier primers will help depends on how much pressure your load makes. Try heavier primers and see.
Click to expand...

Remington ran our military Lake City plant from 1941 until 1985 and then Winchester ran the plant until 2001. Then ATK took over and started using CCI 34 and 41 primers that are thicker in the base. And this is to help prevent slam fires that Remington and Winchester did not have in the past. Meaning Remington and Winchester used their standard primers for over 45 years making 5.56 ammunition without using the CCI 34 and 41 primers.

Below the military drawing for the CCI military primers, you can see the bottom of the primer is thicker and the anvil is shorter than a normal primer. And this take more firing pin force to set the primer off.

n8TOU36.jpg


Below Lake City 5.56 case drawing, the brass used is harder and the flash hole web is thicker to add strength to the base of the case.

JcVlKzc.jpg
 
I have a bunch of Lake city brass ( bought a thousand a few years back) but have been using the thinner Winchester primers.
The pierced primers look closer to your second pic but without the pronounced flowing around the pin.
More just a dark spot in the middle of the indent that appears like a mild amount of gas is getting through.
It's only happened a couple of times and my pin looks fine.
I'll switch to the .025 cupped ones and that should solve the problem. BR primers are sure a lot easier to find locally than the milspec #41 ones.

I'm going to be loading 75gr Hornady BTHPs and Sierra 75gr TMK out of a 16" with the intent to hunt with them so the higher velocity I can get the better. The Hornady 75gr OTMs require about 2200 to perform so I need 2700fps to get them to 200yds at that threshold. The Sierra tipped OTMs perform down to 1900fps so it's a little less critical to max out the speed on them.

I want to wring all I can out of the 5.56, it's a step down from my typical .308 hunting rifles so the best performance I can wring out of the poodle gun the better!

Thanks for all the great feedback!
 
bigedp51 said:
Remington ran our military Lake City plant from 1941 until 1985 and then Winchester ran the plant until 2001. Then ATK took over and started using CCI 34 and 41 primers that are thicker in the base. And this is to help prevent slam fires that Remington and Winchester did not have in the past. Meaning Remington and Winchester used their standard primers for over 45 years making 5.56 ammunition without using the CCI 34 and 41 primers.

Below the military drawing for the CCI military primers, you can see the bottom of the primer is thicker and the anvil is shorter than a normal primer. And this take more firing pin force to set the primer off.

n8TOU36.jpg


Below Lake City 5.56 case drawing, the brass used is harder and the flash hole web is thicker to add strength to the base of the case.

JcVlKzc.jpg
Click to expand...

Yup. Good job :)

But what I was saying to OP was that opinions aren't much help here. He's going to need to try it himself in the end. I'd suspect firing pin is too sharp and/or pressures are higher than he realises, but he's a big boy and he can do as he pleases.
 
jethunter said:
Yup. Good job :)

But what I was saying to OP was that opinions aren't much help here. He's going to need to try it himself in the end. I'd suspect firing pin is too sharp and/or pressures are higher than he realises, but he's a big boy and he can do as he pleases.
Click to expand...

Likely thin primers. The Winchester ones aren't that tough or thick.
I'm pretty experienced so if the thicker BR or #41 primers work I think I'll be in business.

Not trying to go crazy on the loads, but a bit closer to 5.56 performance will get me a bit more range out of a short barreled rifle intended for hunting.

There's lots of great data for TAC, reloader 15 and H4895 for these loads so I'm not exactly in uncharted territory here.
 
diananike said:
Likely thin primers. The Winchester ones aren't that tough or thick.
I'm pretty experienced so if the thicker BR or #41 primers work I think I'll be in business.

Not trying to go crazy on the loads, but a bit closer to 5.56 performance will get me a bit more range out of a short barreled rifle intended for hunting.

There's lots of great data for TAC, reloader 15 and H4895 for these loads so I'm not exactly in uncharted territory here.
Click to expand...

Yes there is lots of load data available for lots of powders. And they all say to start at the starting load and work up, and to back off if you see signs of pressure, like for example pierced primers. Because the people who publish load data understand that not all rifles have chambers cut to the exact same dimensions.

I load 5.56 level ammo in 5.56 chambered rifles. It seems odd that I can load to the same pressure using the same primers and I don't have any issues.
 
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jethunter said:
Yes there is lots of load data available for lots of powders. And they all say to start at the starting load and work up, and to back off if you see signs of pressure, like for example pierced primers. Because the people who publish load data understand that not all rifles have chambers cut to the exact same dimensions.

I load 5.56 level ammo in 5.56 chambered rifles. It seems odd that I can load to the same pressure using the same primers and I don't have any issues.
Click to expand...

Slight clarification. I was getting pierced primers out of my SU16 with a 5.56 load of H4895 behind a 65gr gameking last summer on a hot day. I switched to a milder load of TAC and it went away.

That's what made me think of switching to thicker primers.

I appreciate the advice and will certainly work up my new loads with the new rifle and watch for issues.
 
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