You guys might be on to something as my stainless Omega has the worlds worst crud ring with 777. My rifle has no blowback that I can detect. I cannot shoot a second shot without running a brass brush to clean out the heavy ring that is left. It still makes a ring with the .25ACP conversion and Winchester small rifle primers. Not as bad as with the 209 standard primers but still more than enough to limit the second shot possiblility. Needless to say I shoot very little triple seven. My Omega loves Black Mag'3. (You probably have heardthat before).