Read up on those a bit before you buy. Not all barrels are interchangeable on all frames. Older guns cock when the lever is operated. Newer ones have a draw bar that cocks when the action is broken.
Also, watch for the firing pin sticking in the fired position, which can give you a surprise when you load and close it.
I picked up a .410 a couple of years ago that had been nicely restored long ago. Neat little gun.
