Flat primers mean different things to different people.
I use a magnifying glass while working up loads, and I ALWAYS use NEW brass.
I found the progression in pressures on the premier in the following ways:
A. Round edges in the beginning
B. Round edges with some minor flattening, radius on the primer cup changes radius dia, just barely
C. Edge of the primer starts to get square
D. Edges of the primer are Square
E. Edges of the primer are square and have filled out the radius in the primer pocket, and you may see some imperfections of the bolt face on the flattened primer.
E. In the worst cases, the primers will back out from primer pocket expansion, then flatten against the bolt face, which may also produce gas leakage around the primer. Gas leakage will burn tiny pin holes in the bolt face in the worst cases but often will just leave a black smudge on the bolt face. I have seen cases where there was gas leakage but no visible sign of leakage, BUT you can smell the burnt powder, which is verified by decapping the case on the spot. A large straightened paper clip could push a primer out of the case.
I like to de-prime with a hand tool where I can catch loose primer pockets quickly, so that case with a loose primer pocket does not undergo case prep for the next firing. There are many kinds of cheap hand de-priming tools, and they are worth their weight in gold. Also, you can catch the higher pressures that are expanding the case heads to where primer pockets are loosening up, and make a decision to fire or not fire the loaded rounds with heavier powder charges. Note: some powders have one heck of a pressure spike on the top end of the pressure curve.
I had different kinds of NEW brass Rockwell tested some years ago of the same caliber. There was a 6% variance in the same brand of hardness and a 12% variance spread from all the different brands. So, what this means is that you may make a judgment on the softest Rockwell hardness of the lot or the Hardest. Once you realize this spread in Rockwell hardness does exist over a lot # of brass in your possession, you can make some better-informed decisions on what your maximum load may be.
Reloading at the rifle range has tremendous benefits as you can make changes on the spot to see the results.
Getting set up to reload at the rifle range is not difficult, it is more of a mindset.
Depending on your goals, you may want to start with very tough brass, to begin with where economics has no bearing.
Your learning curve is at a minimum 10x faster while reloading at the rifle range, and using a hand de-primer teaches volumes.
I use a magnifying glass while working up loads, and I ALWAYS use NEW brass.
I found the progression in pressures on the premier in the following ways:
A. Round edges in the beginning
B. Round edges with some minor flattening, radius on the primer cup changes radius dia, just barely
C. Edge of the primer starts to get square
D. Edges of the primer are Square
E. Edges of the primer are square and have filled out the radius in the primer pocket, and you may see some imperfections of the bolt face on the flattened primer.
E. In the worst cases, the primers will back out from primer pocket expansion, then flatten against the bolt face, which may also produce gas leakage around the primer. Gas leakage will burn tiny pin holes in the bolt face in the worst cases but often will just leave a black smudge on the bolt face. I have seen cases where there was gas leakage but no visible sign of leakage, BUT you can smell the burnt powder, which is verified by decapping the case on the spot. A large straightened paper clip could push a primer out of the case.
I like to de-prime with a hand tool where I can catch loose primer pockets quickly, so that case with a loose primer pocket does not undergo case prep for the next firing. There are many kinds of cheap hand de-priming tools, and they are worth their weight in gold. Also, you can catch the higher pressures that are expanding the case heads to where primer pockets are loosening up, and make a decision to fire or not fire the loaded rounds with heavier powder charges. Note: some powders have one heck of a pressure spike on the top end of the pressure curve.
I had different kinds of NEW brass Rockwell tested some years ago of the same caliber. There was a 6% variance in the same brand of hardness and a 12% variance spread from all the different brands. So, what this means is that you may make a judgment on the softest Rockwell hardness of the lot or the Hardest. Once you realize this spread in Rockwell hardness does exist over a lot # of brass in your possession, you can make some better-informed decisions on what your maximum load may be.
Reloading at the rifle range has tremendous benefits as you can make changes on the spot to see the results.
Getting set up to reload at the rifle range is not difficult, it is more of a mindset.
Depending on your goals, you may want to start with very tough brass, to begin with where economics has no bearing.
Your learning curve is at a minimum 10x faster while reloading at the rifle range, and using a hand de-primer teaches volumes.
jk.
Move on to shooting other loads in different rifles. Came back to the 308NM in late June or early July. Temps move up to 95 to 100+. Set and put a round down the tube. Had to get something to open the bolt. Primer had been blown out of the case. I wasn't aware of temp sensitive powders. This was also my first run at increasing my powder loads above the reloading manual max load which I was. I hadn't done much reading about temp sensitive powder. I did some reading and talking to others about what had happen. I changed to H4350 powder. I lost about 100fps, but grouping was still very good or the same. Gave away about 16lb of IMR 4350, and IMR4831 (double based powder). I never used it again. The H powders has my go to powders now. If unknown the H powders are single based powders. I have just of late gotten some other single base powders to try. I like to see what powders are going to make the day for me. I use different primers in my load make up to see how the grouping goes and velocity.
