Standard SR primers vs match/magnum/military

[LR1955]

I have owned AR15's since the early 1980's. I have shots lots of reloads with regular small rifle primers. I have read about the possibility of a slam fire, but I have never had an AR slam fire, or been around anyone who has had it happen. It could happen, but it is not something that I worry about.

Bob R

Has happened to me with AR's and I have witnessed it on the firing line in HP matches. These were the earlier days of the AR being a serious contender in High Power. Guys used to load them with the barrel pointing down on their shooting stool and let the bolt drop. Have seen them go off and blow a hole through the shooting stool and into the ground. Thankfully, rules changed about loading the rifle to having it pointed down range and parallel to the ground.

Have had one or two with the M-1A as well and have seen them with the Garand. Most likely the primer was seated a but long. Don't really know. Wasn't the firing pins though.

I personally won't use anything but a thicker primer for the AR's. For the M-14 I used the Federal Match primers. Never a problem with them.

LR55

[TedBrewer5]

I use Cci 450s and regularly see slight primer strikes on rounds i eject after hunts where I did not fire the round. Happy to have that thicker cup. Just wish I would see them on my lga shelves. Cci 400/41 are available. Don’t want to change over to the 41 especially with the higher expense

[SDW]

Thanks all. Since I have over 1500 of the #400 primers in my inventory with nothing else to use them in, I'll just keep using them with a little extra caution. I originally bought 2K of them, which means I've fired a few hundred so far out of one AR or another. No issues yet.

[AK_Reloader]

I use Cci 450s and regularly see slight primer strikes on rounds i eject after hunts where I did not fire the round. Happy to have that thicker cup. Just wish I would see them on my lga shelves. Cci 400/41 are available. Don’t want to change over to the 41 especially with the higher expense

Any AR platform will allow the firing pin to hit the primer upon chambering a round & leave a witness mark on the primer, since the platforms do NOT have a firing pin rebound spring in the design.
It is not a primer selection/choice issue
ArmaLite AR-10's have a firing pin rebound spring incorporated in the design to prevent the issue.

I've run 10's of thousands of Federal 210's thru M1A's,M1Garands,AR chamberings,Bolt rifles shooting NRA OTC & LR Comps w/o a single primer issue.

[SDW]

Any AR platform will allow the firing pin to hit the primer upon chambering a round & leave a witness mark on the primer, since the platforms do NOT have a firing pin rebound spring in the design.
It is not a primer selection/choice issue
ArmaLite AR-10's have a firing pin rebound spring incorporated in the design to prevent the issue.

I've run 10's of thousands of Federal 210's thru M1A's,M1Garands,AR chamberings, Bolt rifles shooting NRA OTC & LR Comps w/o a single primer issue.

I think the idea is, and this is probably obvious, some primers withstand that 'tap' better than others due to their cup thickness, and not go bang unintendedly. I guess in theory, anything with a 0.025" cup thickness can handle many repeated FP taps without any kind of worry.

I also read that if switching to CCI-400 primers from say, WSR primers, you should reduced the load a little. Interesting.

I don't know if it's just internet rumor, but supposedly (i.e., I'd read somewhere) that CCI does not recommend the #400s be used in an AR-15. Use them only in bolt guns, M1 Carbine, .22 Hornet, and so on. Having said that, I'm the OP here and I've fired at least a couple hundred #400 primed rounds so far and not had a problem. But I also don't make a habit of chambering and ejecting ammunition, then using it later. Once it's in the chamber, I use it.

[Mark611]

SDW, I have also seen the same type of info on the CCI 400 primers, I think its mainly has to do with pressures, correct me if I'm wrong, I have as I have said never had a problem with the Winchester standard small or large primers in any of my gas guns, but I will say I have switched to the #41's in my AR's only because I bought 15k of them, I'm going to continue to use the WLR in my M1A1 308win, IMO if you seat them correctly you shouldn't have a problem, JMO