Full size .357 sig barrel in .40 compact

[datadr93]

My carry piece is a M&P 40c. I have been looking high and low for a .357 sig compact barrel and other than Storm Lake have come up with nothing. The sig barrel would be for range time and not for carry... basically looking for a fun shooter that makes alot of noise and flash. So not looking to pay the extra for the SL barrel.

However, a friend of mine has a factory full size 357 sig barrel that he will sell to me for $50.

So my question, can I safely use the full size 357 sig barrel in my 40 compact? I have seen the SL with extended barrels that are ported or threaded so didn't know if this is really a null issue.

I may or may not have the barrel cut down and recrowned, but if it isn't broke, I won't fix it. Any thoughts?

 

[scattershot]

I just got a .40c, but on mine the barrel has a "boss" or raised portion on the front of the barrel that helps align it with the slide. If the full size M&P is the same way, it wouldn't fit properly.

 

[datadr93]

Nope... straight barrel on both.

Tested with the full size barrel on the compact frame and no issues with brick of .357 sig.

So next, I took my full size 9mm barrel. Measured barrel end with caliber... 0.565". Both the .357 sig and .40sw barrels were 0.565" as well. All three were within 0.001" at the breech block.

Using my 9mm mag, fed 50 rounds thru the 40 compact frame with the full size 9mm barrel... flawless. So that answers my question on using the factory 9mm barrel in the 40.

As far as using the full size barrel on the compact frame, other than 3/4" barrel extending from the frame, no issues. Thus found a cheap way to use the full size .357 sig barrel (that is still available) on the 40c frame. Debating now if I want to leave it as is or have some ports cut into extended end.

 

[Houdini1953]

Well I have both the M&P40 full size as well as the compact I just got my 40 full size off lay away this afternoon after I got off work. I have a storm lake 357 barrel for my compact and I also have a factory 357SIG barrel for my full size and even though I had it with me today I only had 40 and 45 caliber ammunition since I left it at home.

So I can shoot either way with either gun, but I would feel uncomfortable sticking and actually firing through and extended barrel in my compact 40!

 

[datadr93]

I was more concerned with banging the edge of the barrel. But then I see SL also makes an extended barrel for compact with ports or threads and many competition shooters use an extended barrel on their full size to add compensators. I'm just going to use setup for straight range fun and play.

 

[youseemym&p]

definitely a fright for a BG!!! haha tiny pistol 3" of barrel poking out haha reminds me of the noisy cricket on MIB lol

 

[datadr93]

Should not be done as per S&W. M&P barrels are consent at the muzzle. I verified this with calibers and the muzzle is 0.01 thicker the last 1/2". This allows for a tight fit at the muzzle breach. Barrels are made slide specific.

Something to be made aware with conversion barrels.

Thanks for all replies.

 

[clarkstoncz]

So a .357 Compact barrel would probably work in a .40 caliber SHIELD?