H&K usp leak

[Barry Sayer]

I've purchased a new mag for my h&k usp, it's dumping the full co2 bulb in one go after the first shot. The original mag is the same, the seals are all good, plus I lube them regular.

Any thoughts please 🤔

Ta

[JimFromHorsham]

Sounds like the valve knocker in the pistol or magazine valve isn’t returning . 

[Barry Sayer]

1 hour ago, JimFromHorsham said:

Sounds like the valve knocker in the pistol or magazine valve isn’t returning . 

Definitely pistol, not the magazine.

A bent spring found on further investigation could possibly be the problem....will cut it back and temporarily stretch to correct *ish length until I source a new one.

Tested and worked OK. Some hop adjustment was required....it was a mile out dropping about 8 inches at 6yards! Strange how a strip down has thrown it out that much, is that norm🤔

[Anonymoose]

I have one of these and recently found they seem to have a proprietry barrel and bucking. I did manage to modify a Maple Leaf barrel to fit, but still on original bucking.

 

Any idea who the OE is? 🤔

[Barry Sayer]

No, unsure.

How does it preform with the new barrel ?

Have you ever had a problems with yours, I've found it reliable and reasonably accurate to be fair, a good solid pistol ! Nice and easy to strip too.

Edited January 4 by Barry Sayer

[Anonymoose]

I've not yet adjusted the hop with the new barrel, but with just changing that it's brought the gun right up to the 1.13J limit. (285FPS on 0.3s.)

 

I've not really used it much, only issue i had is the pin at the bottom of the grip that retains the lanyard loop/hammer spring kept wanting to come out. I gave it a quick knurl and no issues since.

 

It's my favourite pistol, feels so solid and the grip is just perfect. Like you said, very easy to strip down and work on.

[Barry Sayer]

I think it's called the nozzle return spring that was the problem with mine. How the hell has it deformed I'll never know, its a deep internal part, so its a mystery. Looking at the exploded parts diagram it's part S07. It's a 15mm spring so now is the trauma of trying to find one 🙃 

[Anonymoose]

If you need one quickly and we can still find a replacement i can take the one out my 4.5mm USP. (Assuming it's the same.)

[Barry Sayer]

43 minutes ago, Anonymoose said:

If you need one quickly and we can still find a replacement i can take the one out my 4.5mm USP. (Assuming it's the same.)

Thanks for offering, I'm in no rush for one. I've got it working with the botch chop down and re stretch to fit 💪 😁...crude but it worked, fired a couple of mags through it and was spot on , no leaking 👍

Still puzzles me how its deformed 🤔

[Anonymoose]

Attached a tracer and dial'd in the hop, the range and accuracy now is really good. With 0.3s it's pretty accurate to probably 30+ metres at a guess. (Accurate enough for a pistol, aiming at a person-sized target.)

 

I'm not sure how much of a difference the barrel's made, but it brought the power up so i guess it's a good contribution.