Best primers for 300AAC Blackout.

Candocad said:
^ Thank you very much, this makes for a really good read, there is a lot information there to digest.

Candocad.
Click to expand...

Note the section on .223 primers as it would mostly apply to 300BLK as well, and again the recommendation for CCI 450 primers with it's thicker cup than CCI 400. I've used CCI 400 exclusively for 5.56 loading with nary an issue though. Interesting too the "Note 1" which states that CCI 550 Small Pistol Magnum primers and CCI 400 Small Rifle Primers are essentially one and the same.
 
I've reloaded and shot well over 1000 rounds of 300BLK through four different rifles using CCI400's and never had an issue (only one rifle is bolt action, the rest are semi auto)
 
The most frequent cause of slam fires with the AR15 is if loading a single round without the magazine in place to slow down bolt velocity.
Meaning feeding from the magazine slows down the bolt and lowers firing pin inertia.

It is recommended to use primers with a cup thickness of .025 and using thinner primers increases the chance of a slam fire.

I use Remington 7 1/2 because that was the primer first used at Lake City until 1982 when Winchester started producing ammunition at Lake City.

Below is the print for the CCI #41 primer, the anvil is shorter and the primer has a thicker cup in the base.

n8TOU36.jpg


Bottom line the AR15 has a free floating firing pin without a retraction spring and slam fires can happen.
 
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