Why Magnum primers?

[LRRPF52]

Just one question to add. When comparing CCI SRP(400) to CCI SRMP(450), is the flash(burn) more or hotter or is the primer cup just harder?

Read this thread for fountains of knowledge: http://www.65grendel.com/forum/showthrea...ailability

The CCI 400 has a thinner cup than the CCI 450, therefore, it is more susceptible to slam-fire and and pierced primers. The most common slam-fire in the civilian world is at service rifle matches, when single-loading directly into the chamber, and allowing the bolt to go into battery from lock without any resistance from the magazine-feeding cycle. The increased bolt velocity, especially in warmer temperatures, can combine to cause a slam-fire. The CCI 400's, Remington 6.5's, and Winchester Small Rifle Primers are the culprits, although I have heard of a race-gun AR-15 using a low-mass carrier, low-mass buffer, and factory ammunition with hard primers that would slam-fire.

The shooter had tuned the system to run as fast as possible, giving him an edge on the shot timer against other shooters. $6000 of AR-15 was hard for him to swallow when it kaboomed.

For those that are saying they will just "deal" with the slam-fire after it happens, this is what it looks like. Make sure the range has a good broom and dust pan. Also, please notify the shooters and family members in your immediate fragmentation range that you are disregarding manufacturer and reloading guide warnings about using soft primers in floating firing pin designs, letting them have time to pack their gear or seek shelter:

Garand:



M1A:



AR-15:



Reloading for a gas-operated rifle or carbine is considered by many service rifle shooters to be an advanced stage of reloading, and I can't argue with them. There are quite a few things that you need to really pay attention to that don't apply to reloading for a bolt-action rifle, and those things can result in pictures like you see above.

Primer seating depth
Shoulder Set-back
Full-length Sizing & case lubrication
Primer selection
Powder selection for a gas system
Projectile selection for magazine-feeding
Projectile seating depth

Service rifle vs. bolt gun loads is a huge consideration for the experienced hand-loader, enough so that many big industry names like Hornady, Hodgdon's, Berger, etc. have separate load data sections for .223 and .308 service rifles.

Please wear eye and ear protection if you disregard experienced reloading advice, and isolate yourself to an area free from bystanders, especially on public ranges. It isn't fair to place others at risk. The shooter is in a very safe position with the AR15, but people left and right can receive fragmentation injuries from small pieces of metal and plastic, that only need to pierce an eye to change someone's life forever.