I have built three rifles on Beretta 409 crossbolt actions. Two were 45/70's and one was a 20 gauge bore rifle. One of the actions was a 3 inch gun and I compaired it to the other actions and there was NO measureable differences in the size at all. All of these I have seen are made in the late 50's to early 60's and are very strong and make an excellent choice for conversions. All the guns I converted had had their barrels ruined in one way or another, though. They are worth some serious money as shootable shotguns. If yours is in good shape, I would think twice before converting it. If you do decide to do it, send me a PM and I'll fill you in on some neat ways of doing it. Bob H.