Tuning the HK UMP

jatx · 12-31-2014, 10:25

Hi Gentlemen,

I've not been on in awhile, so it's good to be here.

I know how loud even a suppressed AR can be indoors, so I've gotten my hands on a Navy surplus UMP lower in .45 ACP that I will keep for intimate social occasions. It's just waiting on a Form 1 at the moment, but in the meantime it has a longer barrel. My AAC TiRant will live on it permanently.

The weapon runs great and is in very good condition, but the trigger leaves a bit to be desired. The pull is long and heavy, but there is no creep.

After y'all finish having fun at my expense, I'd appreciate any advice or tips on how to get it functioning more in line with what I have on my good AR's. I am still learning about this weapon system.

Thanks in advance and Happy New Year!

**Team Sergeant** · 12-31-2014, 10:42

Quote:

Originally Posted by jatx

Hi Gentlemen,

I've not been on in awhile, so it's good to be here.

I know how loud even a suppressed AR can be indoors, so I've gotten my hands on a Navy surplus UMP lower in .45 ACP that I will keep for intimate social occasions. It's just waiting on a Form 1 at the moment, but in the meantime it has a longer barrel. My AAC TiRant will live on it permanently.

The weapon runs great and is in very good condition, but the trigger leaves a bit to be desired. The pull is long and heavy, but there is no creep.

After y'all finish having fun at my expense, I'd appreciate any advice or tips on how to get it functioning more in line with what I have on my good AR's. I am still learning about this weapon system.

Thanks in advance and Happy New Year!

What sort of can you running?

jatx · 12-31-2014, 10:44

Quote:

Originally Posted by Team Sergeant

What sort of can you running?

An AAC TiRant once the 8" barrel goes on.

Edit: I have a Surefire on my 10.5" SBR. It's still too loud to go without hearing pro and then hear police commands.

**Team Sergeant** · 12-31-2014, 10:48

Quote:

Originally Posted by jatx

An AAC TiRant once the 8" barrel goes on.

Edit: I have a Surefire on my 10.5" SBR. It's still too loud to go without hearing pro and then hear police commands.

Surefire makes one designed for barrels shorter than 10 inches. I've no idea what it sounds like, I'm sure there's some youtube videos out there.

jatx · 12-31-2014, 10:55

Quote:

Originally Posted by Team Sergeant

Surefire makes one designed for barrels shorter than 10 inches. I've no idea what it sounds like, I'm sure there's some youtube videos out there.

I've got one. It is very nice, but I would not call it "hearing safe" if used indoors. I tried it once and it made a lasting impression!

The AAC is much quieter w/ the subsonic .45.

koz · 12-31-2014, 15:45

You'll need a spacer rather than the spring for the UMP.
Also there is a good link on the conversion HERE

The USC to UMP conversion is cool. If you want something that is just as quiet but better performance, take a look at the 300BLK. You can shoot 220 subsonic's (with a can) and it's just as quiet at the 45 suppressed; Shoot 110gr TSX supersonics and it's a great to 300m.

A few places are going to a 8" 300BLK with a suppressor for all their "subguns" - the benefit is they will carry a few mags of supersonic ammo that can be used when they get out on the street. Take a look at Sig's MCX LVAW. I'll bet it will be in the inventory...

jatx · 01-01-2015, 08:05

Thanks, koz. Those .300 blackout SBR's are definitely cool.

I opted for the UMP because it is one less caliber for me to keep track of, since I mostly own .45 ACP handguns. Plus I don't see much difference between a 230 gr. +P bonded JHP and a .300 Blackout w/ 208 gr A-Max's, since they're both zipping along at around 1000-1050 fps. If anything, the .45 probably retains more weight after passing through most barriers. What am I missing (distinct possibility)?

Of course, this is all moot if I can't get the darned trigger below 13 lbs! In which case, the UMP will become a safe queen for my Yankee friends to shoot on vacations and I will go get a Daniel Defense ISR.

(BTW, my conversion was done by Wes at Black Ops Defense. Despite the company name, he did extremely nice work and was a pleasure to communicate with.)

Flagg · 01-01-2015, 14:02

I've got a H&K USC with a local NZ suppressor on it.

We're lucky we can suppress anything down here without any paperwork or stamp duty.

Our issue is firearms ownership is a privilege rather than a right.

I rate the USC better than the MP5(not a big fan of the MP5 or any other firearm chocker full of metal stampings).

With the local suppressor on it, I would describe the noise signature as fairly quiet, but with a bit of bass to it.

I've used mine for some hunting in close country(pigs/goats within 100m) and carbine shoots on IPSC ranges, but to be honest I rarely shoot it anymore.

I'm looking at consolidating calibers further, and since I've only got .22 and 9mm pistol calibers...this is my only .45ACP, so it's a bit of a loner in the safe.

I'm probably going to swap it for a Steyr AUG(our service rifle), which with a carbine barrel and can on it, still comes in a bit shorter than the USC.

I'll be in the man cave safe in a couple days and will check on the trigger, I don't remember it being that heavy.