HK USC to UMP conversion

[F22_RaptoR]

Mags are here

Barrel is threaded for 16x1mm Right hand threads, same as my HK Mark23, so I can use my fake can on their as well

One thing that strikes me, is that the mags are friggin HUGE! :O

 

[Captain Paul]

That's Manosaurusly awesome

 

[loki_81]

One thing that strikes me, is that the mags are friggin HUGE! :O

Very cool conversion.

Now what round count are those mags pinned to?

I've been doing the footwork on a USC conversion as I was pursuing a stock USC on the EE, which I missed out on by a day, and have been finding out that the parts aren't that readily available anymore. Still got the bug however, and it looks like I'll have to scratch it with a brand new one *sigh*.

I'd like to keep the conversion with the original USC lower as I actually like the smaller mags, but have been informed by Mr. Woverine that the USC mags that they can sell are pinned to 5 rounds. I find that a little wierd as the USC sells with a 10 round mag right? So why would the USC marked mags be pinned to 5 if they don't come with the firearm?

So due to the fact that I'd like to keep the shorter mags it looks like I'll have to go with the HERA arms FSC, or AR-15 stock kit. Would there be any other options for a stock kit that would allow to keep the USC lower reciever? Been in contact with GPtactical, Wolverine, Armseast, and they aren't able to order in the HERA FSC anymore, so I'm contacting blaxsun, but otherwise where would I source the FSC or any other option from these days?

By the way, does anyone have or know of some pictures of the hera arms AR-15 USC stock kit?

Now as for the 7.xx" or 8" barrels, where are people getting them these days? Been in contact with GPtactical, Wolverine, Armseast, and none of them are able to get in a 7.xx" or 8" barrel. Would I be better off ordering a .45acp blank and having a flash suppressor attached?

I'd hate to give up on the project before it starts due to not being able to source the parts I'd like. I know I could get the FBI lower and open the door to the HDPS stocks then, and I really like the folding AR-15 stock, but I don't like the length of the UMP mags, and I don't really want to permanently alter the USC lower reciever.

Ideas?

 

[F22_RaptoR]

Very cool conversion.

Now what round count are those mags pinned to?

I've been doing the footwork on a USC conversion as I was pursuing a stock USC on the EE, which I missed out on by a day, and have been finding out that the parts aren't that readily available anymore. Still got the bug however, and it looks like I'll have to scratch it with a brand new one *sigh*.

I'd like to keep the conversion with the original USC lower as I actually like the smaller mags, but have been informed by Mr. Woverine that the USC mags that they can sell are pinned to 5 rounds. I find that a little wierd as the USC sells with a 10 round mag right? So why would the USC marked mags be pinned to 5 if they don't come with the firearm?

So due to the fact that I'd like to keep the shorter mags it looks like I'll have to go with the HERA arms FSC, or AR-15 stock kit. Would there be any other options for a stock kit that would allow to keep the USC lower reciever? Been in contact with GPtactical, Wolverine, Armseast, and they aren't able to order in the HERA FSC anymore, so I'm contacting blaxsun, but otherwise where would I source the FSC or any other option from these days?

By the way, does anyone have or know of some pictures of the hera arms AR-15 USC stock kit?

Now as for the 7.xx" or 8" barrels, where are people getting them these days? Been in contact with GPtactical, Wolverine, Armseast, and none of them are able to get in a 7.xx" or 8" barrel. Would I be better off ordering a .45acp blank and having a flash suppressor attached?

I'd hate to give up on the project before it starts due to not being able to source the parts I'd like. I know I could get the FBI lower and open the door to the HDPS stocks then, and I really like the folding AR-15 stock, but I don't like the length of the UMP mags, and I don't really want to permanently alter the USC lower reciever.

Ideas?

The UMP mags are pinned to 5, same as the USC ones

The same law change that made the LAR 10-round mags available for Ar15 type rifles, made pistol cal. carbines required to have max 5 round mags... Double edged sword, especially seeing as how I own a .45 cal handgun and it can hold 10, but then again.... these laws were never there to make sense.


As for the barrel, try Bits of Pieces in BC (they're not a sponsor, just google "Bits of Pieces" it should be right at the top). They have .45 cal barrel blanks, and they do 18.5" barrels for the USC/UMP's IIRC, they should be able to do a shorty barrel for you as well, since they're identical in specs except for the length. I got a 26" barrel blank, cut it in half and sold the other half to a buddy, then got a smith to cut/profile it to the same dimensions as my factory USC barrel (except half the length)

Hera Arms stuff is pretty rare, you could always try and export one from the USA... "Dave's Sports Shop" (sponsor at the top) does export work, they might be able to get it from LAN World (although the adapter is 600 bucks US by itself, BUT its pretty much all you need).


If it makes you feel any better, I "almost" sold my USC about 4 times before I hunkered down and started doing the full conversion work to it

 

[Danimal247]

nice build - takes awhil to get used to a collapsable stock on an HK!

 

[Moparlover]

every one of my hk's except the hk 91 have collapsing stocks. 2 ump conversions, a g36 conversion, 2 hk93's and an hk94 all have them

 

[ezkmo]

F22, that looks really good. Very different I like it.
Here is my Hera Arms Conversion, Did not want to go with the ump lower because I had so many usc mags. But I would love to get my hands on a Hera 5/20 mag if anybody know's where I can get one PM me.
Enjoy

 

[Moparlover]

looks great raptor. i just ordered from canada ammo a pair of swissarms cheek pieces to see if i can modify them to fit my stock

 

[F22_RaptoR]

Thanks guys!

The AR 15 stock is definitely different on it, but the CTR is such a nice stock... The adjustable LOP (for our bitterly cold winters, I can shorten it for the 18 jackets ) or lengthen it for prone... not that I'd be able to go prone with the mags

 

[Armourall]

Delete

 

[Armourall]

Ezkmo,

Was the HERA conversion stock slightly lighter than the original USC stock? I've heard they are slightly lighter in colour.

Armour

 

[ezkmo]

If you look closely at the pic, its actually a little darker.
But my usc was died Black, so it's not a good reference.

 

[mugenman]

I've read a few posts on the HK forums - one back in 2009 says that the USC magwell can't be modified to fit UMP mags; however, a second post in 2010 states that the USC magwell can be widened to fit UMP mags if some excess plastic is dremeled/cut/machined away. Anyone have any experience with this or know if the magwell can be widened by looking at their USC magwell? Any assistance would be appreciated.

 

[F22_RaptoR]

The UMP mags are wider than the outside of the USC mag well... Some guys like TBostic or Chopstix_kid on HKpro have added plastic sections to the USC mag well to open it up... but unless you are experienced with plastic welding and milling, you're not gonna be able to do it at home.

Its not something that a home-epoxy-job would be good enough for.

 

[mugenman]

okay, great - thanks F22_Raptor - that helps explain and clarify things.

 

[incorrigible]

The UMP mags are wider than the outside of the USC mag well... Some guys like TBostic or Chopstix_kid on HKpro have added plastic sections to the USC mag well to open it up... but unless you are experienced with plastic welding and milling, you're not gonna be able to do it at home.

Its not something that a home-epoxy-job would be good enough for.

Which has got me thinking...

I know the benefit of the HPDS block is that it can be removed at some point and returned to stock. But as I have no intention of doing so I'm wondering about the logistics of completing a chop like I did with my SL8/G36

It's been a couple of years and thousands of rounds with zero issues so I'm might try it if I can get the stitching figured out. There's not much of a difference in LOP as seen in this pic

... but there is a small difference in how it goes together ie the pin is lower...

There's not much room to stitch in a spine but I think a wide, shallow one might work...

and at the base...

With the end and a small nub for the folder to lock onto and it would be tough to tell the difference.

Now here's the rub. When I replaced my lower I some how misplaced the backplate (#56 on the parts list).

So if anyone has saved thiers, its collecting dust and could help a guy out a pm would put me on track for seeing if this is possible.

 

[F22_RaptoR]

Which has got me thinking...

I know the benefit of the HPDS block is that it can be removed at some point and returned to stock. But as I have no intention of doing so I'm wondering about the logistics of completing a chop like I did with my SL8/G36

It's been a couple of years and thousands of rounds with zero issues so I'm might try it if I can get the stitching figured out. There's not much of a difference in LOP as seen in this pic

... but there is a small difference in how it goes together ie the pin is lower...

There's not much room to stitch in a spine but I think a wide, shallow one might work...

and at the base...

With the end and a small nub for the folder to lock onto and it would be tough to tell the difference.

Now here's the rub. When I replaced my lower I some how misplaced the backplate (#56 on the parts list).

So if anyone has saved thiers, its collecting dust and could help a guy out a pm would put me on track for seeing if this is possible.

Talk to Chopsitx_Kid on HKpro forums, he did just that with a USC/UMP conversion. (he might be able to give ya some insight)

IIRC he used the picatinny rail studs on top to "line it up" and plastic welded the 2 halves together, and it worked out really well. If you're really worried I spose you could get a low profile Picatinny rail (as opposed to the Dlask one?) and use it as a spine and epoxy it on.




For the backplate, is it the piece that slots into the UMP lower and contains the rubber buffer and the recoil rod butts up against?

If so then I have one I can give ya . Shoot me an IM.

 

[incorrigible]

Talk to Chopsitx_Kid on HKpro forums, he did just that with a USC/UMP conversion. (he might be able to give ya some insight)

IIRC he used the picatinny rail studs on top to "line it up" and plastic welded the 2 halves together, and it worked out really well. If you're really worried I spose you could get a low profile Picatinny rail (as opposed to the Dlask one?) and use it as a spine and epoxy it on.

For the backplate, is it the piece that slots into the UMP lower and contains the rubber buffer and the recoil rod butts up against?

If so then I have one I can give ya . Shoot me an IM.

I hadn't considered the stability that he exterior rail would add... good tip, nice! Any other thoughts, feel free to pass them on. There are some of the thicker guages from a spare gap measuing tool that would work on the interior as well if they were slightly milled in and tacked with devcon II. A couple of small allen screws on the bottom flange and a plastic weld would help lock it in place. It's starting to look more doable.

I'm thinking a cut about like in the pic to pic up the top rail screw and enough of the bottom flange to act as a brace.

It was interesting between the rear sight apeture between the UMP (about double) and the USC...

As an afterthought I wouldn't be able to use my orginal .45 lower anymore... I worked hard on that

 

[ezkmo]

Found some Hera 5/20 Mags.

For those Interested contact Blaxsun on this forum. He's the man.

And for those that asked me. Blaxsun also got me the Hera folding stock.

 

[CNADNSL8-5]

Ok, looks like I am about to go full tilt on a USC. It just may not be what you expect. It will be 6-8 weeks before I can get it in my hands.