HK USC to UMP conversion

oenone said:
Don't be so quick to judge a firearm by it's looks. That's liberal thinking, and that is frowned upon.

To expand on that, although the markings on the lower receiver of the USC shown above may appear to indicate «safe», «semi» and «full», that does not necessarily mean that it is capable of all those functions. I would bet that it has the semi USC internals inside, and is not capable of full auto, and that the sear area is filled up, as indicated higher up in this thread.
Click to expand...

i'm far from liberal. i never said it was full auto, it's just just the lower would indicate to me that it was at one time full auto. which in my eyes makes it a converted auto, 12/3 class firearm. just my 2 cents.
 
Yes, this is a common assumption with the USC/UMP conversions with real UMP lowers. I have gone the other route and obtained a UMP lower in "FBI" trigger group with safe/semi only.


"which in my eyes makes it a converted auto, 12/3 class firearm. just my 2 cents." (Moparlover).......you have one of these conversions.........no? You should know that is not the case. Never was,never will be "fullauto"...end of story. The lower is just a gun part...the upper is the issue. If you were using an upper from a fullauto capable UMP and converted it back to semi.....then you would be in the realm of prohib status.
 
Moparlover said:
i'm far from liberal. i never said it was full auto, it's just just the lower would indicate to me that it was at one time full auto. which in my eyes makes it a converted auto, 12/3 class firearm. just my 2 cents.
Click to expand...

No. It cannot be a converted auto firearm, because it never was full auto. Confused yet? Ok, maybe this will explain it better:

In the USC case, the part that is attached to the barrel and has the serial number is the firearm. Commonly, that is known as the receiver. Other firearms may have a different configuration.

Everything else is just parts. the barrel, bolt, stock, mag, and the lower receiver are all just parts. Yes, the lower receiver was maybe at some point in time configured for full-auto. However, it is just a part, and not a firearm.

Thus, because converted auto designation can apply only to firearms, and we have decided that the lower is not a firearm but a part, the combination of the UMP lower, that maybe at some point spewed multiple bullets with one pull of the trigger, and the USC upper, that never ever even dreamed of such a thing, remains a pure, semi-auto design, never converted.

The only difference between the semi lower receiver and the other lower receivers other than the internals is the pictograms on them.

If you like, you can stencil onto your firearm's selector «Safe», and «Pearl Harbour» either in pictograms or in words, but at the end of the day, it means nothing, because setting your firearm to «Pearl Harbour» and then pulling the trigger will not cause Zero's with a red circle on them to attack a certain island in the Pacific (I hope).

If it bothers you or you worry about it, you can wipe off the «Full» pictogram with acetone, leaving just «Safe» and «Semi». Make sure to cover the other pictograms with tape, or you will wipe them off too.
 
to put it simply, the USC receiver cant use the sear in the UMP lower without being cut.

Now if you go and cut your receiver so the sear will work, you WILL have a converted auto.

But as long as you dont cut into the receiver (behind the mag well opening) then theres no way it can fire full auto, even WITH a fully functional Navy or auto lower. It just wont fit.



Many people DO take the Navy lowers and put the USC parts into it, so it can have the look of an auto gun, but will only shoot semi-auto. You can take out a part that lets all the positions (besides "SAFE") shoot on semi-auto. So you have a "Safe-Semi-Semi-Semi" lower :p


Thats one of the reasons many people put the epoxy into the Sear area on the lower, so it physically cant accept the sear. I did this on my FBI (semi-only) lower, but it wasn't a requirement.
 
well how's about this? my HK94 has a 2 position lower and has a registered upper, the same as my usc/ump. if they were available here and if those parts were installed on it, it will change the class. example, if i put the 3 or 4 position lower on the upper, even though i didn't repalce the trigger pack, it would now be 12-3 class converted auto. and if the trigger pack and bolt were changed out, it would be 12-2 full auto. i wouldn't assume that they will see it any differently at the RCMP or CFC. seems to be a lot of wishful thinking here. again, just my interpretation of it.
 
Well Moparlover....."if,could be,might be" are all variables that you feel should be considered.....correct? Again,my question to you is.....don`t YOU have one of these USC conversions? If so, what did you do to overcome YOUR concerns with the alledged "converted auto" issues that so plague you?

I could also make all my Glocks full auto (approx 1200 RPM) if I so desire.....doesn`t mean that I will.......just because I have a G17C (complete with 32 rnd mags that are pinned to 10) that looks exactly like G18 doesn`t mean a damn thing! I could also make a buddies M1 carbine full auto...again....it ain`t gonna happen......are you sure that you like guns?

As everyone has clearly stated....the USC upper has to be modified to fire full auto...nobody is going to do this. As for your HK 94.....I am not familiar with it. If simply changing the lower would make the uper fire fullauto and they interface with no modification...then there certainly is a difference between the two platforms isn`t there?
 
rajczak_kashka said:
Well Moparlover....."if,could be,might be" are all variables that you feel should be considered.....correct? Again,my question to you is.....don`t YOU have one of these USC conversions? If so, what did you do to overcome YOUR concerns with the alledged "converted auto" issues that so plague you?

I could also make all my Glocks full auto (approx 1200 RPM) if I so desire.....doesn`t mean that I will.......just because I have a G17C (complete with 32 rnd mags that are pinned to 10) that looks exactly like G18 doesn`t mean a damn thing! I could also make a buddies M1 carbine full auto...again....it ain`t gonna happen......are you sure that you like guns?

As everyone has clearly stated....the USC upper has to be modified to fire full auto...nobody is going to do this. As for your HK 94.....I am not familiar with it. If simply changing the lower would make the uper fire fullauto and they interface with no modification...then there certainly is a difference between the two platforms isn`t there?
Click to expand...

That wouldn't do it for the HK94 either. You need a different bolt, and you need to modify the Grip housing (or the receiver) for a full auto trigger group to fit. You might be able to get a trigger pack into the HK94 grip frame, but you still need the full auto bolt.


As for the USC, its opposite of the AR15.

Its like having a full auto bolt in your AR15 with a semi-trigger group. It still cant fire in full auto without heavy mods to the gun. You can do ANYTHING with enough time and effort. The USC has enough measures to safe guard it from being fired in anything but semi-auto.


However if you're that concerned with a Navy trigger group, then do the epoxy/pin trick and fill the sear area with epoxy, that way the sear can NEVER be put in again.
 
For the USC (and SL8), you have a few things preventing full auto firing:

-trigger group is semi-auto
-receiver will not accept full-auto bolt
-the bolt is not full-auto (will not interface with trigger group to support continued fire)

Some people have the UMP (and G36). It has only has one thing preventing full auto, and that is that the trigger group is semi-auto.

Does that mean that the UMP and the G36 are 12/3 firearms? No. Without modification, they will not fire in full auto.

If you really want to, and I do not suggest this, you can tie a string between the trigger and the charging handle of the Garand, looping it around the trigger guard so that with forward movement of the charging handle the trigger is pulled. Shall we ban string now?

It is easy to take anything to the absurd, but as long as you do not make your firearm fire more than one round with one pull of the trigger, you should be fine. That is what the law wants to prevent: Fully automatic firearms in the hands of civilians.

The HK USC is not your grandfather's HK94, and thus it is not viable to compare the two from a legal perspective.

Stop worrying and enjoy the USC.
 
Pics

Here are some (lousy) pics of the completed UMP as well as a few other recent aquisitions:

GUNSMARCH003.jpg


GUNSMARCH009.jpg


GUNSMARCH008.jpg


GUNSMARCH007.jpg


GUNSMARCH005.jpg


GUNSMARCH001.jpg


008.jpg


013.jpg


012.jpg


011.jpg


UMP build consists of:

- HDPS stock block B
- HK UMP FBI lower receiver (semi auto,safe only)
- HK UMP buffer
- HK UMP accessory rails (all)
- HK UMP folding stock
- Trijicon night sights for UMP
- HK UMP .45 mags (25 rnd@5)
- HK vertical battle grip
- HK UMP 7.87 barrel in .45
 
Last edited:
Looks awesome man! :D

Now I just cant wait for the machinist to get working on my block. He said it'll be a half-day project, so hopefully once he GETS to it, it'll be done quick.
 
rajczak_kashka said:
Here are some (lousy) pics of the completed UMP as well as a few other recent aquisitions:

011.jpg


UMP build consists of:

- HDPS stock block B
- HK UMP FBI lower receiver (semi auto,safe only)
- HK UMP buffer
- HK UMP accessory rails (all)
- HK UMP folding stock
- Trijicon night sights for UMP
- HK UMP .45 mags (25 rnd@5)
- HK vertical battle grip
- HK UMP 7.87 barrel in .45
Click to expand...

Any thoughts as to what optics you're considering... if any?
 
optics

I have tons of optics to choose from. I am inclined to go Aimpoint Micro T1 or M2 Comp though. Eotech 553 or 552 look a bit clumsy. Kinda regretting the sale of the 511.a65 now.....lol.

The Trijicon Reflex RX01 looks good on this weapon ......decisions...decisions?

I like the clean look as well.........this is an awesome gun.


Had a bunch of old compatriots over tonight to swap "war stories" and such..... a night of French Vodka....German automatic weapons and Polish Rap music......what more could a guy ask for? Wife was not impressed though and she is Polish....lol
 
F22_RaptoR said:
Looks awesome man! :D

Now I just cant wait for the machinist to get working on my block. He said it'll be a half-day project, so hopefully once he GETS to it, it'll be done quick.
Click to expand...

If you give the machinist the spec sheet for the mag well enlargement...well....go about a 1/16" bigger on each side for width as I had to open mine up with the Dremel to accept the UMP mags. Works flawlessly now.

I am going to the range...I hope on Saturday with my 10 year old son to try the HK UMP out....will let you know how this goes....
 
You must log in or register to reply here.
Back
Top Bottom