40S&W converts to 357 sig?

[Dangerwing]

I've read little bits and pieces of forums and articles that alluded to the idea that a 40S&W could fire (or easily be converted to fire) 357sig. Same kind of idea as 357mags firing 38spl. I was reading mostly about H&Ks. Has anyone heard of this before? Any truth to it? If so, what convertions are needed if any?

[Mosin44az]

A different barrel is needed for the conversion between .40 and .357 SIG.

[oldbillthundercheif]

You could fire .357 Sig rounds from a .40 S&W from what I understand, but the extremely undersized projectile would just sort of rattle down the bore. Accuracy would be abominable and I bet the velocity would be quite low from the gas venting around the bullet. Probably not a good idea.

There are lots of replacement barrels and maybe springs as well to convert pistols between the two cartridges, though. From what I have heard it's usually an easy conversion.

[Mosin44az]

I recall SIG had a conversion kit offered for a time that consisted solely of a different barrel, i.e., the springs and mag didn't even have to be changed.

[G20]

in a Glock all that is needed is drop in barrel ,mags use the same !

[urf]

The sig P229 just needs the barrel changed to the desired caliber. The sig P229 magazines are interchangable with the .40 or 357 sig round. The above applies for the sig P239 except, the magazines must be caliber specific to the barrel being used. I hope this information was/is helpful. PS I learned this first hand.

[9x19]

Yep... I have a .40 barrel, made by Storm Lake Machine, for my Glock 31 (.357 Sig)... simply swap barrels, use the same mags.

[kristop64089]

Are there any downsides to doing this? I have heard negative comments on converting but just wondered about doing so. I have an xd-40, I really want a sig .357 sig but, can't afford one right now.

[urf]

I have not had any downsides except that the ammo is kind of high in price.

[fairview mick]

I have a standard Sig 226 that came as a .40 cal from the factory. I bought a factory .357 Sig bbl, also from Sig. The Mag's are the same(even marked as such). There is NO DOWNSIDE from shooting a .357 in a forty frame. You can't go that way from a 9mm to a .40 or .357, though. I also had Barsto make a "Semi Drop in" (9mm) bbl for that gun which is masterful piece of work. I don't shoot the .357 cartridge as much as the .40 or 9mm because of cost. The .357 Sig is a great bullet, though.
Mickey

[JohnKSa]

At least one company (Beretta) recommends that their .40 S&@ model 96 pistols NOT be converted to .357 SIG.

[9x19]

The downside?

You may find you prefer the .357 to the .40! :D

[briang2ad]

you could fire a 357 SIG in a 40 is ridiculous.

It would SEEM that this cartridge would be the IDEAL manstopper akin to the 357 magnum. But... the 40 is here in a big way, and it can mimic a 357 load AND makes a bigger hole.

[JAXX]

What would the benefit be of a .357 SIG over .40 S&W?

[TxPhantom]

I saw a Sig Sauer, 357/40 caliber for sale at a gun show for a little over $500.00 that I've always regretted not buying. It was factory reconditioned with full warranty and had interchangeable barrels.
My M & P 40 caliber has 357 and 40 caliber stamped on the magazines. The magazines will hold either but it would take a 357 barrel to make the conversion. S & W is supposed to come out with the 357 conversion barrel soon (or someday). I want one when they do.

[kristop64089]

Other than having the option to shoot a seperate caliber, is there ant advantage to conversions? (is the .357sig that much better?)