Have to go lead free in the next few years for hunting.
That's my situation, but it's immediate (past) for me in A-Zone. The Green Enforcers would not be pleased to find a leaded .45 on my hip even if my hunting arm was a rifle with compliant ammo.
I understand your concerns, but you're talking more conservatively than I'll act. But I'll be cautious. (Famous last words...
)
Overall length, powder space, and bearing surface will all be guesstimatedly factored in.
One good thing is that I've no need to 'maximize potential' right now, just put together something not unuseful. If I need to step out on my own in the short term, I can be conservative; and wait for better info later on which to build a premium load.
