Hello All,

I am interested in getting the capability to use my P320 (RX, in 9 mm) with 357Sig ammo.

Do you I need a full conversion kit, or can I replace only some specific parts and if yes, what are these please ?
Obviously the barrel, but what about the Slide, recoil spring, etc... ?

Also, I looked for conversion kits (Sig or MidWest Gun works) and they seem to be sold out ..
Any other possibility ?

Thanks a lot !

This message has been edited. Last edited by: Leonard17F,

If you want to shoot 357Mag ammo, you need to buy an entirely different gun and probably a revolver, but certainly not a P320.

If you're referring to 357SIG, you need a conversion kit, if you can find one. Otherwise, you'll need an upper, and magazines. Looked on GunBroker?

If you're referring to 357 Magnum, buy a revolver.

Two entirely different critters. I assume you are looking for .357 Sig, which would mean you'd need a conversion kit, as others have said. That will include a new slide, barrel, recoil assembly, and magazine.

As to things being sold out...welcome to Sig. I am a fan of the P320, but my one complaint is it can be a real PITA to find parts. I've been looking for subcompact magazine baseplates for over a year, and I can't see where Sig has ever sold them as a separate item. Other stuff I've shopped around and eventually found, but it was a lot harder than it should have been.

If you can find a used .357 Sig upper (Slide, Barrel, recoil spring assembly) on eBay or GunBroker, that would work for you...you'd just need to buy some .357 Sig mags from another source.

I’ll assume that you are referring to 357 SIG, not Magnum which would be impossible as far as I can imagine.

The slides for 357 SIG and 40 S&W P320s are not the same as 9mm 320 slides. The former are somewhat heavier, and they are designed for the 357 or 40 barrels which are larger in diameter than 9mm barrels. The 357/40 barrels are about 0.570 inch in diameter whereas the 9mm barrels measure about 0.550". A 357 or 40 barrel will not work in a 9mm slide.

Therefore, to use 357 SIG ammunition with your P320, you would have to have a proper slide in addition to the barrel. Recoil springs intended for 357 or 40 are stronger than 9mm springs to reduce slide velocity with the more powerful ammunition, but a 9mm spring would probably work. SIG cartridge conversion kits include the slide, barrel, and recoil spring assembly.

The 357 SIG is an excellent cartridge that I prefer for carry. Some loads approach or equal the ballistics of some loads of 357 S&W Magnum, but not the most powerful. Unfortunately, SIG Sauer seems to be drawing down its support for the cartridge because factory barrels are becoming difficult to find. If, however, one has a conversion kit for 40 S&W, a 357 SIG barrel might be available from aftermarket manufacturers.

If you find a way to convert your pistol to 357, note that you do not need “357” magazines. P320 magazines for 357 and 40 S&W are exactly the same.

Thanks a lot for your previous replies.
I meant 357Sig of course
Really appreciate your inputs
Leo

FWIW, hit the "edit" icon on your first post and you'll be able to edit the thread title.

Oh, and it may be worth your while to shop around. I found a "certified, pre-owned" P320F in 357SIG at a local show for about the cost of a conversion kit.

quote:

Originally posted by Il Cattivo:
I found a "certified, pre-owned" P320F in 357SIG at a local show for about the cost of a conversion kit.

You make me cry!

quote:

Oh, and it may be worth your while to shop around. I found a "certified, pre-owned" P320F in 357SIG at a local show for about the cost of a conversion kit.

This is an excellent point as well. IMO, the biggest problem with the "modularity" of the P320 is the price and availability of the conversion kits. Often you can buy a whole CPO gun for similar or even less money. Makes no sense.

Thanks a lot Everybody for your great inputs !
Really appreciate !

I converted mine (P320C) from 9mm to 357Sig via a trade with a member here.

Slide, RSA, BBL & Magazine

Not sure if you could just drop a 357Sig BBL & RSA into a 9mm slide...

quote:

Originally posted by P250UA5:
Not sure if you could just drop a 357Sig BBL & RSA into a 9mm slide...

Ah …, no:

quote:

Originally posted by sigfreund:
The 357/40 barrels are about 0.570 inch in diameter whereas the 9mm barrels measure about 0.550". A 357 or 40 barrel will not work in a 9mm slide.