I have a USP compact .40 and I noticed in the manual it was talking about a .357 sig? Can you order the barrel from HK and switch out your .40 cal barrel? Remember I'm just a newbie so don't persecute my question to ruthlessly.
I'm not sure if HK still stocks the .357 Sig barrels seeing as they recently discontinued importing the USP Compact .357. But well worth a try contacting them and "yes" it is pretty much a straight drop in. You can even use the same .40 mags for .357 Sig ammo!
ML SEC PRO might be able to get them from HK. Chances are you can get a high quality aftermarket barrel cheaper, be wary of buying too cheap though, I bought one for about $85 and was sorry. My factory SIG barrel performs excellent in my 226, it came as a 357 with a 40 spare barrel.
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