Hello OB,

I recently purchased a HK USC 45 carbine from a good friend of mine. He lives on the other side of the country but before he moved we made an agreement that he would give me first rights to buy if he ever decided to sell it. He contacted me a month ago and we agreed on a price and I picked it up on Friday. I

My original plan was to do a USC to UMP conversion on it . Much to my surprise when it arrived it had already been converted to a UMP stock and a grease gun magazine lower, the last time I saw the rifle it was a bonestock USC.

So I was wondering if you all think I should invest the money in doing a proper UMP conversion or leave it as is. I shot it over the weekend and it runs just fine. The only thing I don't like is it doesn't hold the bolt open after you fire the last round. Any advice you have would be great! Thanks and Gig'em.

Congrats - sweet rig especially one converted to UMP off the bat

Not sure what it might lack for a 'proper' conversion - maybe milling the vents? Now that it's yours tho you probably want to make sure it's was built to 922r compliance.

You can google USC to UMP conversion and find some good write ups for a 'proper' conversion. Look at HDPS and Tommy Built builds

As to your bolt open question - check your bolt catch, spring and pin. Not too expensive to replace.

Some Links including manual -

https://hkparts.net/?s=Bolt+catch+&post_type=product (scroll down to 'UMP, USC')

http://pdf.textfiles.com/manuals/FIREARMS/hk_usc45.pdf

https://www.hdps.org/htm/5-3-1.htm

Thank you for the advice. Time to take it apart and see what parts were used int he conversion. I think I will end up SBRing it...it just doesn't look right with a 16.5" barrel.

Yep much better as an SBR!

Maybe your buddy has an invoice from a shop or his receipts to help document 922r? But since it started life as a USC and still has the original barrel I'm sure you're fine!

I think I will get a trust established and file to SBR my Scorpion and USC...I am committed to the PCC now.

Get the conversion done correctly. It'll be worth more to someone.

I wouldn't worry about 922(r). If the feds are charging you for violating it, you have bigger issues because they're likely also charging you with something much worse.

Thanks for the reply. Is Tommy Built the best company for UMP conversions? Or are there better options?

Tommy is good but I'd start with HDPS I think he's a little more economical

I know HDPS is set up to help you complete a conversion you can mostly do yourself but I assume tommy will do the same

Thanks! I'm about to head over seas for a few months, so ideally I would like to ship it off and have it built while I am gone. I have about 60 days to work all this...

good luck and God's speed - stay safe