M&P 40L Conversion To 357 Sig

[CW4RETIRED]

Searching for 5" barrel conversion from 40 cal to 357 Sig. Pistol is the Performance Center M&P C.O.R.E. 40L Pro Series with non-ported 5" barrel. SKU: 178059.

Has anyone done this conversion or can you point me in the right direction for resources to accomplish this?

Thanks

 

[colt_saa]

I would think that a telephone call to Bar-Sto or any of the major barrel manufacturers would get the ball rolling with no problems

 

[k2ue]

I have a 5" 357SIG using a Storm Lake Barrel in a 40S&W 5" slide. Works great, put many rounds thru it in regular IPDA-style shooting. If you don't want to wait an extra month or two for the Black Oxide option, you can significantly darken the barrel with the Caswell Stainless Steel Blackener Gel Kit. Or use it as-is, if that suits you. You can probably order one thru Special Orders at Brownells, ask for Storm Lake SW-MPP-357-501 and they will get a quote for you. I see they no longer list it in the Storm Lake online Catalog, but they may still be available.

 

[OKFC05]

KKM makes the exact barrel you want, and that's all you need to change. Use the same mags.
KKM | L/Pro .357Sig

 

[k2ue]

KKM makes the exact barrel you want, and that's all you need to change. Use the same mags.
KKM | L/Pro .357Sig

I have had 2 issues with KKM 357SIG barrels in the past:

One had a chamber so tight that it would not accept a full-length resized case that would pass a case gauge. I wound up buying a chamber reamer and it did take more metal out of the chamber.

Another had questionable heat treating and became visibly peened on the locking surface at the top front of the chamber -- using factory ammo.

I would guess both of these issues have been fixed in current production, but it's worth keeping an eye on.

To be fair, my first Storm Lake 357SIG barrel clearly had a CNC mistake -- I sent them a picture of the barrel in a slide with something like a 0.030" feeler gauge inserted showing the excess headspace -- it was promptly replaced.

I now make sure I have a GO/NO-GO headspace gauge set for each caliber I use, and check all new barrels before use.