Primer softness causing slam fires in AR-15 platform?

[NevadaZielmeister]

Gentlemen,

I recently received my Short Barrel Rifle and mounted a suppressor on the rifle. It it a short stroke piston LWRC M6A3 with an AAC M4-2000 suppressor. The barrel is 10.5 inches long and I am using 5.56 ammunition.

I recently have found out that I was getting slam fires on my reloads due to the soft Federal #205 Small Rifle primers being used in LC once fire brass and Varget powder. The system was somewhat over gassed and it would slam the firing pin into the primer (however lightly though) and the rifle would go full auto for about 3-4 shots. Using regular ammunition, such as PMC, alleviated the problem.

Question: Are there different levels of primer softness/hardness? Does the Federal Match AR Primers address this issue of slam fire in semi-automatic rifles? Which primers are people using in a similar make up?

It should be noted that my HK MR556 AR-15 running a Surefire FA-556AR on a 16.1 inch barrel does not have this problem.

 

[CMH]

Have you looked into trying to find some CCI 41's? Mil-spec, hard primers. May be just the ticket for what you are looking for.

 

[KUSA]

Get some Remington 7 1/2, they are hard as hell. Check the chart out. Primers And Pressure

 

[wilecoyote]

Generally Federal primers were considered quite,if not the most, sensitive_ so sensitive that Lee once warned against the use of Feds in their priming/reloading tools_
I agree that CCI never have caused any slam-fire problem in any of my semi-auto reloads _ that even with the normal CCI or BR type CCI; for sure, the mil-spec variety will be even less sensitive_ That assuming that your LWRC be in good mechanical shape, of course_

 

[NevadaZielmeister]

Get some Remington 7 1/2, they are hard as hell. Check the chart out. Primers And Pressure

Wow, this is EXACTLY what I was looking for. Thank you so much for finding this. I searched and search over the web and nothing found. My suspicions regarding slam fire are confirmed when the primers I would using were the thinnest of the group.

Thank you for your help KUSA.

 

[rweaver00geo]

I had some slam fires with cci's. Rem 7 1/2 cured that, haven't been able to get a hold of the cci nato spec until recently

 

[NevadaZielmeister]

Have you looked into trying to find some CCI 41's? Mil-spec, hard primers. May be just the ticket for what you are looking for.

I found 5000 on MidwayUSA for $195.99! Bought a brick and will have ready for the next 5 cases of .223. Thank you so much for the info!