09-02-2013, 04:46 PM
PrecisionFirearms Wrote:We recommend using CCI M41 Primers in all loads for the 5.56 but not for the 223. Using a Magnum Primer with load data designed for non-magnum primers is good way to get a medical bill or at the least a Gunsmith bill. The M41 is a Milspec primer and has a harder primer cup to prevent slamfires and a hotter primer charge to help with cold weather ignition. Having discussed this with Bill at AA and CCI, we have come to the conclusion that the CCI 41 primer is basically the same primer charge as a CCI 450. I have used both in our 6.5 Grendel loads. Have not had any issues with either, except for some rifles with match trigger in which the hammer springs were lighted to decrease trigger pull. Then the Hammer didn't have sufficient energy to ignite the harder M41 Primers. We have since gone to all CCI 450 Primers. One item we did learn is that using Federal primers had a tendency to "empty mags real fast". So they are a no GO!!. Another experience lesson - Always use M41 or M34 Milspec primers in 308 based AR's and compensate for the magnum charge by reducing the charge weight by 10% and working back up from there. (I can tell you how to do that in a gas rifle but that is a another subject!) The firing pins are heavier and they will slamfire a lot easier! Just got done diagnosing that issue with a 243 Win AR we built recently. The 308s didn't have the problem, but the loads we have developed for the 243 did, due to using Benchrest CCI primers. We are working on a firing pin fix to correct the problem.
Is anyone using milspec primers and experiencing failures to ignite in their bolt guns?