Quote Originally Posted by tomme boy View Post
If you used 41 cci primers then that is your problem. Not only are they thicker the anvil is spaced out farther to prevent slam fires. Regular 450 mag cci primers are the same thing as 41 but the anvil is in the standard location as the 400 primers. 400 primers are not meant to be loaded in 223 or 556 ammo as it is thinner and was designed for 22 hornet class of cartridges.
What your saying is very true for Small Rifle Primers but in FOGeologists' case and mine with our 243s, LRPs were involved.