I have a two SIGs and bought a .357 barrel for a 40 cal from Bar-Sto. Mine will be ported but a threaded unit costs the same as I recall. I deliberately bought an MT barrel that will require fitting but they do sell what they call "semi drop in". Those may or may not require minor fitting.

I'm no expert but Bar-Sto does have a very good rep for quality. My barrel was $245.00 USD and the fitting could be another $1/200.00.

I would NOT recommend getting something chambered for one caliber and using it for another under ANY circumstances. Though the barrel length is what you are wanting it for, the chamber portion is NOT designed to handle the pressure of a .357SIG discharge, nor is it the correct shape to begin with.

Check with BarSto or another vendor, don't be an accident waiting to happen over wanting to put a can on a handgun. There ARE parts out there to do what you want safely. What you suggested just isn't.

The amount of material is exactly the same for either. The chamber and barrel bore are centered on the firing pin, so expanding the chamber from 9mm to 357Sig will still be lined up to the center of the bore. As for putting a can on the end of it I have been designing and fitting muzzle brakes for rifles for over ten years. A good muzzle brake or compensator is a very big plus for accuracy and better practice. Its enough of a difference that the recoil spring will have to be changed to a lower strength.

Sounds to me that your mind was already made up before you posted. If you aren't going to follow the advice you asked for, why ask for it in the first place?

Let me get this straight. You want to use a 9mm barrel and re-chamber it to a 357 Sig? So you will have to remove material yet it will be able to handle pressures much higher than what the barrel was built to take. Just how is that supposed to be safe? I mean, a 9mm is a high pressure load but the 3257 round has a good bit more and you are going to have to remove material to make it all work. Sounds to me like it's not a gun you want to rebuild. It sounds much more like you are going to build a grenade. I just do not believe that making a chamber bigger is going to keep it as strong let alone be stronger to handle the added pressure.

Now being I don't know for sure I sent a message to a good friend of mine that is a gunsmith and was a tool and die guy. I have not heard back from him yet tonight but will post his reply to this when he does. It was me I'd not try it. But I trust this guy. If he says it can work and work safely I'd believe him. He's the only person to work on any of my weapons besides me. I'll post his answer when I see it.

The exterior dimensions of the barrel and chamber block are the same size for 9mm and 357 Sig, they are interchangeable in the 226. The only material to be removed in the chamber body is the lower section of the bottle-neck round. The PSI test pressure and brindle hardness are the same. I just though that it was a good idea to get the creative, inventive juices going...I built a wildcat rifle cartridge years ago, the 6mm/284 Madd. It turned out to be more efficient than the other 243's...more velocity and less powder in a smaller case. About the same time Bill Shehane was working on one very similar, and he posted some great scores out to 1000 yards. I like to tinker..and that's what keeps the shooting community growing and the industry growing. Just my 2 cents worth. Good shooting, Gary.

The exterior but what's the distance between the edge of the chamber and the outside edge of the chamber? That's where I'd be worried. If the chamber is weaker even at the back end of the case it would be good info to know jut how much material you can remove from the chamber and still be able to hold pressures from the rounds being used. I guess what I'm getting to is would Sig Sauer use the same barrel blank to make both barrels?

BTW: My tool maker friend is out of town. So I have not heard back as of yet.

I believe that Sig uses the same barrel for both chamberings.

I just bought a P226 after a lot of serious shopping and comparing, and the 40 and 357sig are interchangeable on this, but NOT the 9mm by everything I have read so far.

you'd only be removing .56mm of the chamber (all around). the barrel would be more than capable of dealing with the increased pressure.

however the bolt face of the 9mm and the 357 sig are not the same. the length of bullet protruding from the casing is not the same. (6.99 in the sig and 10.54 in the 9). the length of the cartridges are different. you could most likely get the chamber to match the 357 sig, but you'd have to extend the chamber slightly into the rifling. would the barrel handle it? probably. but where you run into issues is the bolt face and slide. bolt face is smaller than the sig. it'll never properly put a round into battery, fire, extract or eject. could it be shaved down to fit? possibly, but reliability is going down with the metal you take off.

heres the ultimate worry though. will the barrel even lock properly? if that casing sticks out a little bit, preventing the slide from going all the way forward and locking the barrel in place then you don't have a sealed chamber. pull the trigger and all hell might come back at you, especially if for whatever reason the path of least resistance is rearward instead of forward.

the weapon was not made for that round, period. you're far better off investing the money into a sig weapon that is already chambered for the 357 sig