I have a question I hope you guys can answer for me. I have A Stevens 311 20 gauge. I would like to get a set of 12 gauge barrels for it. I know that the 311 receivers are the same for all gauges. My question is--assuming that the barrels are not excessively worn will these barrels interchange without a lot of fitting required?

There is a VERY small chance that they will fit well enough to use without careful fitting, Mike. Kinda like hitting the lottery. A very few guns, Valmet being one that comes to mind, are much more likely to be barrel interchangeable with little to no fitting. Very close machine tolerances are what contributes to the possibility this will happen. Stevens just weren't held that close.

But, you might get lucky.

SRH

Oh, pardon my poor manners. Welcome to the board, on the occasion of your first post.

Hello Mountain Mike
Welcome on your first posting

I did not know that the 311 rreceivers were the same for all gauges.

Again
Welcome
Mike

My thinking on the 311 without actually having one at hand to check is that the bar & basic action is probably the same on all gauges, but the width & height of the standing breech would vary according to gauge. If this be the cast then they would not interchange from gauge to gauge.

I didn't either. I had a 20 gauge that wasn't.

I have read that the receivers were all the same, but my personal experience is different. A set of 12 gauge barrels I had would not come close to fitting a 16ga I owned.

I have 311's (stamped 5100) in 20ga, 16ga and .410 and a Fox Model B (basically the same gun) in 12ga. They're not in front of me but I don't believe any are the same size. I think Miller is right; some of the dimensions are the same but not all.

While I did not say so in my first post obviously the firing pin centers would also be different for each gauge. This difference becomes obvious on the .410 as the breech is little wider than the action body behind it. Probably the hammers are the same but the firing pins would set at different angles. Not having any in front of me but just going on recollections of those seen this would seem to be the case.