A few years ago I bought 1,000 LC .556 cases that had been reamed, cleaned, sized and primed. In the bag that was packaged with them it contained the end tab of the CCI 41 box to indicate the type of primer used.

A review of the CCI web site indicates the use of the 41 primer in military applications is to address the issue of slam fires and constitutes a tougher primer metal to avoid such detonation on contact with the bolt before the action is in battery. It seems to indicate that the equivalent CCI primer is the CCI 400 Mag. Yet many of the vendors selling these once fired military brass, that sell them primed, are using the CCI 400 primer.

Questions:

1. What is the burn rate equivalent to the 41? Is it the 400Mag or the 400?

2. How interchangeable is the 400 to the 41?

3. Is the only difference between the 41 and the 400Mag and 400 is the toughness of the metal used?

Here's what CCI says:

•Mil-spec sensitivity
•Initiator mix optimized for ball/spherical propellants
•Available in large (No.34) and small (No. 41) rifle
•Use the same data as CCI Magnum primers

I always figured they were closer to a standard and not the mag primer. But I"ve been wrong before.

Pretty much a tougher cup magnum primer.

The 400 is a soft primer that a lot of loaders won't use for an AR. I haven't had any problems with them but every gun is different.

The 450 is a a little thicker cup and hotter primer for ball powders. I've ran two companies small magnum primer in different loads.

The 41 is a thicker cup than the magnum cup.

I don't know how much of a difference in how hot they are from standard to magnum. Winchester used to make two rifle pimers, large and small. They didn't make a magnum.

As far as interchanging them if you work up a load with the 41's your fine. The load may not be the same with a 400. If you have a near max or max load running, I'd back it off and rework it.