+1 What Wick said, for the simple reason muskets, and a lot of trade guns had very large locks, with double throated cocks, and were built to handle more abuse. The lock is an engine designed to put sparks in the pan. Rifles, and fowlers have locks generally with thin single throated cocks that are pretty slim, and a bit more fragile. The use of lead could effect the operation, but there is no specific proof. It's more just what they did 200 or so years ago. As has also been said try both make your own decision.
Bill