Use plumbers tape, AKA strip lead. Use a bit of rubber cement to stick it in the lower barrel channel. You can try differing amounts and locations 'til you find the right formulae. I would then hollow the butt to balance the gun. You can always correct with a little extra weight in the butt if you over bore.

I have several guns with hollowed butts - no problems in over 25 years.

C Man
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