Reread my post, I said ”The sad thing is, these rounds were the tightest pattern to date for this rifle.
As far as me not knowing how to make safe reloads…you don’t know me or how I reload. You don’t know how many charge weights I developed before this problem arose. In 20 years of reloading, this is the first time I ran into all of these particular issues. Hence, the my posted question.
I said that I would back off 1/2 to 3/4 of a grain. Why those amounts you might ask…because, I have already fired those charge weights and had ZERO issues.
I found early on that my 243’s would go from optimal accuracy, to case damage and worse with surprisingly small powder charge differences, so I can relate.
Even smaller .223 and 6 BR cases wouldn’t react quite as adversely as a .243 to the same amount of additional powder beyond what’s optimal.
I have run ratios of powder charge to bullet weight in my competition cartridges, all utilizing heavy, high BC bullets.
The .243 has the highest ratio of powder weight relative to bullet weight of all my cartridges utilized in Fclass guns from .223 to .338 LM.
Consider, for example, that the .243 is basically the same case and capacity as a .308, but a heavy bullet for a .308 weighs about twice as much as a heavy bullet for the .243. Going the other way, a heavy .223 match bullet is slightly less weight, but just over 1/2 the powder charge of a .243.
Stated another way, the .243 uses more powder per grain of match bullet, to get it up to speed. I’m not sure, but I think this implies greater inherent resistance to bullet acceleration in a .243, which implies, - as they all use brass - that the brunt received by .243 brass is already relatively higher than in other cartridges loaded for match purposes.