help on leading problem

[osiek]

255 gr .377 sized WWcast 10 gr unique in 375 winchester bore slugged at .375.5 very bad leading of bore. changed to 11gr Herco same thing . Should i size them smaller? it has enough lead when brushed it flakes out

[runfiverun]

379....

[uscra112]

Yep. size 'em bigger. You need to fill the throat of the chamber, which may be 3-4 thou bigger than the groove diameter.

You also need to completely de-lead the barrel before you shoot any more lead in it. Any lead still there will just create more fouling no matter what you do. (I dare you to ask me how I know that one!)

Aggressive brushing with copper Chore-Boy (not the copper-plated steel ones!). Fine steel wool on an undersized brush will do, but it's not as gentle to the bore as the Chore Boy. Or if it's not too bad, just shoot 3 or 4 full-power j-warts through it, then clean thoroughly with a copper-removing solvent. That's what I do. Works.

[MtGun44]

Bigger is almost never a problem. Smaller is almost ALWAYS THE problem.

You want about .002 or .003 larger than groove diam for rifles.

Bill

[GaryN]

All good advice. Also, did you clean your bore spotless before starting? If there was any copper in there before you started it can cause problems.