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Based upon twist and weight I'd guess your Tolley is a conical bullet gun. Have you tried 750-800 grain conicals?

You say your round balls are gouping 2" apart at 50 yards. What happens at 100 yards? Assuming you have unaltered original sights, are the impacts high or low vs POA? Does relative accuracy of the barrels hold out? How far apart are the balls at that distance. I think you will find out what is really going on if you quickly move up to 100 yards for testing.

I'd go with Gatsby's suggestion for the 8 with wheel weight balls. You may find that undersized (.015 under) pure lead balls group better. I would not worry about aerodynamics of the round ball, we already know they stink.

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My questions as well. Elevation is very important - and where the barrels print horizontally at 100, etc.

The 12 bore round balls are very close with group centres only 2" apart at 50 yards so a slighlty lighter, or slightly heavier projectile might be needed. Lighter is easier and cheaper to test first as diffeerent ball sizes should be readily available from guys involved in reinacting groups. .690", .715" and .735" are nominal sizes of moulds easily available form Lee and Lyman, with any size available from Tanner in England - about 7 day shipping to the States and Canada for about $35.00 US.

At 2" apart- is that crossing, or diverging? If diverging, they're probably diverging only 1/2" at 50, therefore only an inch at 100" from parallel? Aren't the bore axis's about 1 3/8" to 1 1/2" apart? So parallel groups would have 1 1/2" between group centres? Just a thought. 2" sounds very close if diverging. If crossing, well, that's different.

Daryl

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Daryl


"a gun without hammers is like a Spaniel without ears" King George V

Edited by Daryl_S (18/12/11 05:02 AM)

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