I didn't mention that in those .58's at that time (which is why I included the dates), I was using powders that Lyman listed in it's handbook (black cover) - GO & Curtis & Harvey and I also used Meteor (Made in Scotland) which also was garbage powder. Lyman loaded right to 190gr. GO in their ZOUAVE with .562' round balls and .020" patches and that load developed only 8,100LUPressure at 1,700fps.
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They also loaded to 150gr. with 570gr. bullets in the .58's- using GO powder. Do these compute to today's powders - NO! In that .58 Hawken with the Large barrel, I was running 675gr. bullets with 160gr. of 2f GO. for 1,325fps - they kicked a bit more than I liked.
Since you know how to load decent components, Dan, I doubt very much you'll get 'blown' patches with any load you can or would use in a .62.
Accuracy is another thing - hard to say - one of those must-do things.
What's a heavy charge for a .62 using today's powders?
Both my .40 and .45 rifle barrels have 48" twists. Both barrels run over 2,200fps when using LHV lube and both shoot their best at that speed - with LHV lube, whether I am using 3F or 2F.
I'm glad it's coming back to the market. I have 1 bottle left. Only problem with LHV is it demands more powder to get it to shoot it's best but once there, man does it shoot!