H&K

[TonyD]

Okay all you pistol guru's, riddle me this... Can a H&K USP 9 be converted to a 40 cal? Yes, no, why, why not, what is involved?

I'm not looking for guesses or conjecture. I'm looking for someone with positive knowledge. This is my first inquiry as I haven't contacted H&K yet.

Thanks.

 

[drgrant]

Most 9mm pistols (regardless of manufacturer) cannot be converted
to .40 or .357 sig, usually because the slides are too different in
weight. (They're too light, and the mass is too low to deal with the
extra pounding of the bigger cartridges.) The breechface of the pistol is
also too small to accommodate a .40 S+W/.357 Sig case head.

You can go downward (from .40/.357 EG with a barsto 9mm conversion barrel) but
not upwards. Even then the downward conversions are not considered "carry
ready". (because parts are not exactly in spec, etc. ) When doing a
downward conversion, the recoil spring must be lightened considerably to
ensure halfway decent function.

Note that this doesn't include oddball conversions WRT switching the entire
upper of the gun. You -might- be able to do a conversion that way, but
that's generally not feasible from a monetary standpoint, especially not
with an HK where "spare" uppers are hard to come by. (they usually only
exist because someone destroyed their frame with a KB! and ended up
buying another pistol. )

FWIW, HK is a bitch to get parts from. I doubt they'd sell you an entire
upper. I don't even think you can get sundry parts from them like sear
springs and the like, let alone a whole upper.

-Mike

 

[TonyD]

Thanks, Mike, but this is why I was hoping for more definitive info. The USP 9 was built on a .40 frame. In others words, HK designed a .40 cal pistol then changed parts to accomodate the 9mm. I'm thinking that at most I would need to change would be the barrel, slide and magazines but was hoping someone had some first-hand knowledge.

I'm actually hoping because HK built this as a .40 the slide would not need be changed. Not sure on how the breech face and extractor would work.

 

[drgrant]

Thanks, Mike, but this is why I was hoping for more definitive info. The USP 9 was built on a .40 frame. In others words, HK designed a .40 cal pistol then changed parts to accomodate the 9mm. I'm thinking that at most I would need to change would be the barrel, slide and magazines but was hoping someone had some first-hand knowledge.

I'm actually hoping because HK built this as a .40 the slide would not need be changed. Not sure on how the breech face and extractor would work.

Even if the slide was nearly/exactly the same weight you still have
the breechface problem. A 9mm slide does not have a wide enough
breechface to accommodate the .40 S+W casehead. I know for a
fact that the USP9 breechface is indeed only cut for 9mm casehead.
I don't know of any 9mm handgun that has breechface that's too wide, in general. )

I agree that the -bare frames- are probably -EXACTLY- the same, but
then things get funny from there on out. If the ejectors are different,
you're essentially screwed because on a USP the ejector is pretty much
molded into the frame. (At least the last time I detail stripped one of
my USPs, I was unable to remove that part, as it seems like its part of
the frame. )

Remember that, -anything- is possible, it's just a matter of the lengths
you would go through to do it.

-Mike

 

[TonyD]

Even if the slide was nearly/exactly the same weight you still have
the breechface problem. A 9mm slide does not have a wide enough
breechface to accommodate the .40 S+W casehead. I know for a
fact that the USP9 breechface is indeed only cut for 9mm casehead.
I don't know of any 9mm handgun that has breechface that's too wide, in general. )

I agree that the -bare frames- are probably -EXACTLY- the same, but
then things get funny from there on out. If the ejectors are different,
you're essentially screwed because on a USP the ejector is pretty much
molded into the frame. (At least the last time I detail stripped one of
my USPs, I was unable to remove that part, as it seems like its part of
the frame. )

Remember that, -anything- is possible, it's just a matter of the lengths
you would go through to do it.

-Mike

Very true and all that makes sense. I'm just thinking I could have two firearms by a simple swap of the barrel, and slide, and of course, the magazines, much cheaper than purchasing a complete weapon.

Sort of like the .22 conversion for a 1911.