I don't have or load for a .204, but protruding primers, especially with new brass, is often a sign of low pressure. The firing pin drives the minimum dimension case forward into the chamber and the moderate pressure is enough to cause the case walls to grip the chamber walls and for the primer to back out of the case and contact the bolt face, but not enough to cause the case to set back against the bolt face and reseat the primer.
I looked at some H335 data for the .204 after reading your post and it looks like the starting loads and maximum loads in some instances are within 2 to 2.5 grains of each other. One source listed a starting load pressure of 47,000 psi and a maximum load pressure of 56,000 psi with H335, and your load was closer to the starting load than the max load from that source.
So, assuming your rifle's headspace is within spec, it could simply be that your pressures are relatively mild and those new cases are just not fully obturating to completely fill the chamber.
I am certainly not saying that you should get carried away increasing your loads, but I have often seen backed out primers with mild loads in new brass. An excellent example is the 8mm Mauser when used with lightly loaded US factory ammo. The 8x57 in military loads is a real barn burner, producing more power than .30/06 military loads do. However US factories load it to just about duplicate the .32 Special, and I have often seen protruding primers after firing those wimpy factory loads.
Last edited by wildhobbybobby; 03/22/10.
