I spend all my time on the shotgun side of the forum, but I thought I would ask this here.
I have Hollenbeck Three barrel guns with rifle barrels in 30-30 and 32-40. Should I be concerned about using copper jacketed bullets? I strongly prefer them for their performance on game, quite frankly a .30 caliber pure lead slug makes me a little nervous. On the other hand I do want to treat the gun properly as well.

Marks-21,
If I were you, I wouldn't be concerned. The 30-30 was always loaded with jacketed bullets, and bullets for 32-40 (usually 32 Win.Spec bullets) are soft enough for the rifle.
Mike

I have nothing of real value to add, but always looked at the Hollenbeck, Three Barrel Gun Co. , and Royal drillings and thought the rifle chamber area, and actually the whole barrel looked smaller than comparable calibers in other guns. I did not take any measurements.