Since chamber pressure testing equipment/components vary even for the same bullet weight (test barrel length, groove diameter of test barrel, leade length/free bore of test barrel, case wall thickness, primer flash intensity/duration, bullet length/nose profile, bearing surface length, bullet seat depth, etc.), I think we will continue to see variations in the published load data.
It would be ideal to reload with the same exact components as the published load data so to duplicate the same chamber pressures with same seating depth, intensity/durarion of primer ignition, etc. using new/verified once-fired brass but often this is not possible and we must conduct our load development/powder work up with whatever components we have on hand.
Due to these reasons, I think if a reloader uses mixed range pick up brass with unknown reload history and condition of brass, use of more conservative published load data would be adviseable for the initial powder work up/load development especially for 40S&W and faster burn rate powders.
1KPerDay said:
Nothing I've tried up to this point has made these bullets shoot worth a darn.
I know this may be off topic and I may pursue further discussion on a different thread, but you have been puzzled by varying degrees of accuracy with Berry's 180 gr plated bullet. I have been pondering and perhaps occasionally more accurate shot groups you have been getting from the same batch of reloads may be from particular group of reloads with similar condition/dimension cases.
This would be hard to check unless you have enough verified once-fires brass. I save verified once-fired brass and can send you some with same lot/head stamp for further testing if you like. I am planning to do some RN vs JHP accuracy comparison range test over the Christmas week and can do some test for you with Berry's RS/TCFP bullets with same/different powders.
