Quote:
Originally Posted by pantannojack
I just read the thread about Alliant 2400 vs hercules 2400, with various primers resulting in differing pressures. It refreshed in my mind my question regarding how most printed manuals recommend lower charge levels when using lead bullets compared to jacketed ones.I savy the possibility of leading and progressively increasing pressure as leading worsens, but wonder does the possibility of the lead projectile increasing in diameter under pressure increase resistance in bbl travel? I am casting 158g Lee gas check bullets sized .357 from whatever mixture I have in the pot lubed with some red stuff requiring about 100 deg. Never pure lead but some WW, some lino, some salvage with tin added. I like the HS 7 @ 10g as recommended by Hodgdon but with F100 std primer, and 15g IMR 4227 also std primer. My loads are not showing any bbl leading at all.
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No easy answer and lots of changeable factors, the main reason(s) cast bullet load development is often extensive. The search for the right alloy and right bullet diameter for the load will pay off with freedom from leading and fine accuracy. There aren't really aren't any shortcuts if you do it right, unless you just get lucky and hit upon the perfect bullet for the load from the start.
As for the pressure you mention, I think there often is a greater pressure rise with cast bullets as opposed to jacketed, but staying short of maximum loads, it's probably insignificant.
A number of years ago, I spoke with one of the Lyman guys who was involved with shooting and pressure testing for their load manuals. I wanted to know how much pressure difference there was in increasing bullet diameter by a thousandth, as in going from a .358" bullet to a .359". Granted, a general question, not taking into account changeable factors, and I received an equally general response that the pressure difference was slight. For my purposes, that's fine.
If you have a load that's not leading and accuracy is good, you may have arrived where you want to be or are very close to it.