If I could find a m357 I would do that, however it’s hard to find one. The m357 were not that popular so there might be trouble sourcing one.

 

Where are you located? I found a 357 sig M9 at my local gun shop. It looks like it was barely used.

 

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357 or 9 mm?

Can a 357 barrel mount on a 9 mm?
As far as I know, 357 and 40s can be interchanged, but not on a 9 mm frame.
RCM offers 357 barrels and there is a european barrel maker.

Glock 40 and 357s swap and you can mount a 9 mm kit on them, but they will not promise reliability with the 9 mm.

 

The 9mm slide cannot take the 357 barrel, you need a slide marked .40 slide or .357. The frames are the same, you can put a 357 or 40 slide onto a 9mm frame. So basically you need a .40 or 357 slide, then a rcm barrel and you can put it onto a A2 frame, which so far is only 9mm.

the problem is finding the mag/slide for a .40/.357. Outside of that while you can place it onto the A2 frame, you still have the A1 extractor.

 

I may be thinking of the S models which had different lengths at least at one time according to the Steyr site.
Of course Steyr also calls the handguns double action.
I have an M357 barrel also.

 

Ok, to clarify, I have a complete M357-A1, with RCM barrel as a spare.
I am looking to see if anyone has insight on outfitting M9-A2 to shoot 357S using any parts necessary from a complete M357-A1.

 

All you have to do is throw the 357 upper on the A-2 frame. Just did it to my 3rd M40-A1 after grabbing a cheap A-2 from berreli before Christmas. You can also completely swap the receiver module between frames if your A1 module is marked 1.5 (I don't know about earlier modules).

The A1 mags work fine in the A2 frame. But if you want to use your A1 frame with the 9mm A2 upper and mags, you'll need to change the A2 mag base-plate and keeper for an M&P base-plate and keeper (some material may need to be removed from the back of the new base-plate to fit in the A1 frame, depending on which M&P plates you buy). You'll also lose 1 rnd of capacity from the A2 mag unless you buy an extended M&P base-plate (or cut coils off the A2 spring, not recommended).


Edit to add: I did have an issue with the latest A2 frame having trouble locking back on an empty m40 mag. Turns out the slide lock spring on the A2 is bent to have a stronger downward force (probably because the A2 mags have stronger springs than the A1 mags). Changed the spring and lockbar between the 2 frames and now it works fine.

 

Thank you for sharing your experience.