Mike, Welcome to this forum! Standard rifle barrels were in .30-30, .32-20, 25-20, and .22 Hornet. The .25-20 is hard to find and the .32-20 is very rare. Shot barrels were available in 12, 16, 20, 28, and .410. Late barrels will work on all models, but early barrels that are made before the "B" suffix models, may fit later actions but will not cock the hammer. Please be cautious in your search. If you have time please share some pictures of your gun. Thanks for sharing with us. Best wishes, Garnett