USP Expert Sticky Trigger Reset

[Bobby Ricigliano]

USP Expert Sticky Triigger Reset
Hello all,

Any help or tips regarding this issue would be appreciated!

I picked up a BNIB USP Expert .45. I noticed before I ever shot it that the double action trigger reset would sometimes hang up and require a gentle nudge before returning to double action mode. If I completely let off the trigger after the hammer drops, the force usually returns it to battery as it snaps forward. However if I keep my finger on the trigger and ride it forward, the trigger will often stop prior to returning to battery. With the slide off I inspected the lower for obstructions along the trigger bar on the right side and nothing seems to be obstructed or damaged.

I test fired the weapon and it shoots like a dream, with the trigger in DA and SA both being superb and flawless operation. It just seems odd to have this issue in such a high end gun.

Question: Is the trigger reset in DA mode when new? Does the gun just need to be broken in? I fully lubed the gun as well to make sure lubrication is not an issue.

[huckberry668]

None of my USPs (Experts, Elite, Tactical) have this issue. The trigger return spring is a bit on the light side on these models (expert, elite & tactical). Put a few rounds down range and see if that smooth things out a bit. If not, send it back or replace the trigger return spring.

[Mr310]

Sometimes the USP will come with the trigger not fully unlocked from the factory and requires a quick jiggle of the key in the magazine well to fully loosen it up. Pics please! That's a beautiful gun.

[swamp2]

I have the same pistol. Congrats on finding a BNIB one they are getting a bit rare. Although I have not specifically heard of nor experienced this problem I would recommend a thorough cleaning of the composite frame/trigger/safety/decocker.

A great method I have found for a composite semi-auto is to completely soak the entire frame assembly (after a basic field strip only) in a non evaporating cleaner. I've even found that a water based, non evaporating cleaner like Simple Green works great (without the last key step here this would normally be a big no-go due to water content). Once soaked use a variety of small brushes, q-tips, etc. To reach into all of the moving parts and nooks and crannies. Some compressed air during the process will help remove dissolved materials as well. You can rinse with lots of hot water and simply repeat with the cleaner, tools and compressed air until the frame assembly is spotless.

Now the key - bake the gun at a very low temperature, about 200 degrees F for about 20 minutes. This is WELL below the temperature to damage any part of the pistol and will evaporate ALL of the water from your cleaner or rinsing. Just FYI, I am a former physicist and former Mechanical Engineer and a bit of a perfectionist when it comes to firearm maintenance. If anyone tells you this procedure is a big mistake or some other such rubbish consider them uninformed.

You'll be amazed how new and spotless hour frame assembly will look after this. Finally add some low viscosity lubricant to all of the right spots (a syringe works great for some of the hard to reach spots). I prefer Slip 2000 EWL.

If this does not solve the problem you might consider a full detail strip, clean and lube. I've attached a good guide for that.

Of course if you can afford to wait a while without your pistol, H&K will evaluate, test and repair for you.

[RippSpeed]

I use to have this issues after installing a few match/lem/hybrid competition triggers on a few of my friends HK's ... But, it usually worked its self out ( break in ) after a few hundred rounds.
My own personal HK USP had this hiccup after swapping over from a lem to a version 9/ sao match trigger. But after a few hundred rounds in a uspsa match and a good cleaning after the new trigger spring settled and went away...

[Bobby Ricigliano]

Thanks to everyone for the replies!

I will check the trigger key that it is fully unlocked, give it another thorough cleaning, and put a few hundred rounds through it this weekend. Hooe that does the trick because this one is a keeper.