Sig caliber x-change kits

Racer Doug14 · Dec 18, 2018

I have a P229 in 40S&W. I'd like to find the Sig kit to swap to 9mm. Sig currently does not show them on their website. Has anyone done this conversion? I know certain frames can't accept the kit. I'm gonna call Sig with my ser# to check later. Also, to find out if they even make them now.

photoracer · Dec 21, 2018

Racer Doug14 said:
I have a P229 in 40S&W. I'd like to find the Sig kit to swap to 9mm. Sig currently does not show them on their website. Has anyone done this conversion? I know certain frames can't accept the kit. I'm gonna call Sig with my ser# to check later. Also, to find out if they even make them now.

You won't be able to do it with just a Sig factory barrel. If they do make a kit it will have a .40 profile barrel and a .355 hole in it. Several aftermarket barrel makers make this kind of barrel for Sig and HK firearms but they don't include a full kit if needed so you need to look into getting your own 9mm recoil spring and mags if needed.
I did that with my original HK USP-C, but its easier. The recoil mechanism on the USP-C is different than the standard USP as it has a recoil buffer. My gun was chambered in .357Sig so for .40, HK actually sold the OEM barrel by itself as the mags are the same and the recoil setup handled the .40 also. When I went to add 9mm I found that HK did not make a replacement barrel which would need to be thicker for the slide hole (as I mentioned for your gun earlier). So I went with the Dragonfire 9mm conversion barrel. Turns out the original recoil assembly is still good and the .40/357Sig mags handled 9mm just fine. Now I also have a full size USP (Combat Competition model) and in this case the gun is a .40 and I want to add both of those. However .357Sig USP barrels are scarce while aftermarket 9mm ones are not. And they say the mags might be "iffy" for 9mm. So a lighter recoil spring maybe needed. This USP came with 10 16 rd. mags and I don't want to have to buy new ones if possible (Jet Funnel magwell also). So you may have to build your own kit. First the barrel then a lighter recoil spring then maybe you will need 9mm mags also but try to borrow first for a test.
Funny, my old Sig P229 Sport model was in .357Sig. At the time I never considered getting a .40 barrel because this gun used a threaded barrel with a factory comp on the end, much less a 9mm barrel.

Racer Doug14 · Dec 21, 2018

Thanks for the reply. I'm pretty sure I'm gonna abandon the 9mm swap. I've decided to do a couple of low cost upgrades for this pistol. I'm probably going to get a M11-a1 or P229 SAS to fill this want. I still like the .40S&W. Also, a .357SIG is a option. Blaster seems to like it.

Fox123 · Dec 21, 2018

Shoot me a pm if still interested

rbird7282 · Dec 21, 2018

I have an M11-A1 I’d be willing to sell if you’re interested.

Sent from my iPhone using Tapatalk

Racer Doug14 · Dec 21, 2018

PMs sent.

Racer Doug14 · Dec 31, 2018

Thanks to Fox123, my 9mm P229 conversion was realized. Perfect fit to my W.German frame.

Racer Doug14 · Jan 6, 2019

So I'll summarize this.

If you have a 40S&W legacy pistol, with a W.german made frame. The Sig 9mm Caliber X-Change kit will probably work. Mine did. I dont see a lot of reasons why it wouldn't. The locking block could be a concern. But, that is easily replaced. Mine was fine. It is a more expensive option, but not by much. The fitting of the aftermarket barrel would be a big PITA for a shade tree gunsmith.

If you can find one cheap, go that route.

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