View Full Version : USP45 Slide Stop Failure

05-27-2012, 11:25 PM
My USP45 has never had any problems. I just took it to the range a couple days ago and it worked fine. Got home, cleaned it like I normally do and now the slide stop won't lock the slide back for any of the magazines I have for the gun.

I've taken apart and reassembled the gun a couple more times (just to make sure I did it correctly and that nothing looked obviously broken) and I haven't seen anything wrong but it still won't lock the slide back.

Any ideas on what happened?

05-27-2012, 11:28 PM
Do you break down and clean the magazines regularly also? If the mags are dirty they won't always push up the slide stop

05-27-2012, 11:29 PM
It is likely the mag springs. Get some wolff springs and you are back in business.

05-27-2012, 11:36 PM
Thanks for the quick replies. I'll take a look at the magazines, though I do find it curious (and unlikely) that all three of them would fail at the exact same time. Is there anything that could have happened with the gun itself that could cause this?

05-27-2012, 11:51 PM
Check to see that the slide stop itself is not broken. Does the follower push up on the slide stop when you are trying to lock the slide back?


05-28-2012, 12:00 AM
Yeah try the mag without the slide on the frame. Take the slide off put the slides top in the frame ind insert mag, and see if any part of the follower touch the slide stop.

05-28-2012, 12:08 AM
The slide stop seems to be fine. I did what duc suggested and the magazine pushes the slide stop into what would be the path of the slide. It seems with the slide installed, there is more force holding the slide stop down and the magazine doesn't provide enough umph to get it into the slide notch.

Again, it would seem it's the magazines but the magazines' springs seem to be pretty damn strong and I find it crazy that all three mags would fail at the exact same time.

05-28-2012, 12:09 AM
Can you post some pictures? especially with the slide pulled all the way back and where the slide stop is when you do that with a mag inserted.

05-28-2012, 10:03 AM
Nope didn't happen, impossible! Usp45 can not fail ever. Sorry to hear your troubles, I have never had multiple magazines go bad at 1 time. Thinking about it probably could stand to replace my springs.

05-28-2012, 10:10 AM
The slide stop catch, or the slide notch could be rounded so as not to catch the slide stop? Or, perhaps the little arm on the follower that pushes up on the slide stop would be bent?

Good luck,

05-28-2012, 3:56 PM
Looked it over again. Everything seems to be working fine with the slide stop. Without the slide on it, the magazine pushes up the slide stop. It seems the magazines are just not strong enough to push it up... so I'm replacing the magazine springs. Just weird it happened in all 3 mags at once.

Oh, and the USP is awesome. Never had a FTF or a jam (and the gun was made in '99). I like it so much I just bought an HK45C.

Thanks for the help everyone.

05-28-2012, 7:03 PM
Weird indeed but I hope the mag springs solve the problem. :thumbsup:

05-28-2012, 9:11 PM
This is a somewhat common problem with HK USPs in 45 ACP---it's the magazine springs---replace with Wolff springs---problem solved!