Converting a HK 40 S&W to 357 Sig

[JSM]

Can this be done just by replacing the barrel and possibly the magazine? I understand that this is doable for brands, but HK's? I also know that the max pressue increases from 35K for the 40 S&W to 40K for the 357 Sig. Let me know.

thanks, Scott

 

[Jubei]

I know that for the Sigs and Glocks, all that's required is a barrel change, you don't even have to change the magazines since the base of the .357sig is essentially a .40cal. The only thing that I would imagine you may have to worry about is changing to a stronger recoil spring, I know that the Glocks and Sigs don't.

I would contact HK and ask them.

Jubei

 

[PO2Hammer]

357 Sig just didn't work reliably in the USP. H&K tried it as did aftermarket barrel makers, but the rounds would nose dive too often coming out of the feed lips and jam against the feed ramp.

 

[Winzeler]

357 Sig just didn't work reliably in the USP. H&K tried it as did aftermarket barrel makers, but the rounds would nose dive too often coming out of the feed lips and jam against the feed ramp.

I have a Fire Dragon ported 357SIG for my H&K. It works well provided certain conditions are met. First, it doesn't work very well in cold conditions when there is likely to be that very fine condensation on the cartridges. Second, it will nose dive any JHPs that I have used, though it fires FMJs fine. Third, the magazine takes an extra bit of time to load because I need to make sure none of the cartridges are criss-crossed in the double stack magazine. It's easy to push the nose of the previous round down into the mag as you load the next. This can cause the nose dive effect talked about by someone else.

If all these conditions exist it fires quite reliably for me. As for carry, I will not put any other ammo in it that the Pow'rball stuff from Corbon. Everything else only gets one shot because the FMJs cram right into the bottom of the feed ramp. The most reliable way for it to be set up is with 12 rounds in a 13 round magazine.

All that said, it does, in fact, work. You just have to learn the tricks. It's nowhere near as versatile as the factory .40 barrel, but I don't hesitate to carry with it in the summer months with Pow'rball ammo (568ft.lbs. according to Corbon, by the way).

 

[Onmilo]

It strikes me as humorous and perhaps a bit intentional that Heckler and Koch cannot get a leading European competitors cartridge to work reliably in a pistol of their design,,,,,,,

 

[kirkcdl]

I have 2 guns in the "dual-caliber" configuration.(357sig/40S&W).One is a Sig 239,and the only problem(not really a problem) I have is the 40 ammo won't fit in the 357 mags,it appears to be a difference in the feed lips.I also have an HK USP Compact that originally was a 357sig gun,I added a Firedragon 40 barrel.I have had no problems with either caliber,with the exception of shooting reloads in 40.The 40 reloads I use are a bit underpowered,so I blame it on that,factory loads run fine.The rounds will fail to fully chamber,and stop at an angle,halfway in the chamber.All it takes it a slight nudge on the slide and everything's fine again for a few rounds.I do not have the mag interchangeability problem with the HK.My next "dually" will be the EAA Witness,the only thing holding me back is I don't know whether the available drop-in barrels are full size or compact.Hope that helped...

 

[PO2Hammer]

I have a Fire Dragon ported 357SIG for my H&K. It works well provided certain conditions are met.

I wonder if it had anything to do with the full size USP magazines and their plastic feed lips, about the only ones in the industy I believe.