From reading the recent posts it sounds as if the USP's are usually reliable.  My new one has problems!  None of the mags will reliably lock the slide back.  Even more of a problem, out of about 80 rds I had 5 failure to feed problems.  Any one have advice or similar problems?

Have you ever noticed how many loose chickens there are in Europe? It's because all of the gun manufacturers stole all the chicken wire to make mag springs for 10-round-only U.S. mags!

Actually, the first thing I would do is take the magazines apart and clean them.
and spay the inside and follower with some fast drying silicone spray.
If you still have problems, then you probably have springs that are too weak to push the follower up enough after the last shot.


Since you have two problems that can be caused by weak springs, you might want to try some Wolff springs.
www.gunsprings.com/SemiAuto/HecklerKoch.html#USPMags

Try this with an empty gun and mags. Slide forward, insert empty mag, pull slide to rear and see if it locks. If your mags are new, and un-tampered with, this should work. If the slide locks open with all mags when trying this, the problem most likely is in your grip...you could be putting pressure on the slide catch with your thumb under recoil. (Probably your support thumb unless you have very large hands)

If this does not work, disassemble the mag(s) and check to be sure the spring is inserted correctly. Typically, the "high" end should face the front of the mag...very common for guys to reassemble the mag with the spring backward, and although this will allow feeding, it often will not allow the follower to engage the mag catch.

Another thing that could cause this with a new gun is that the gun is "dry" and needs lubrication. NO ONE seems to understand that a new gun should be cleaned and lubed correctly before it is shot. Manufacturers are much more concerned with storage of a new gun than in it being correctly lubed for use. Make sure this is not your problem.

I have never had a problem with factory H&K mag springs or magazines in any of the several I have owned, nor with the .45 USP i own now.

I too, have never had a problem with mag springs right out of the box. If it does it with all three springs, it is most likely the gun not the mags. Check the slide lock or slide release lever and make sure it is moving freely. It could be binding. If you are using low velocity ammo, the slide may not fully cycle back far enough on that last shot to lock back. Its rare but can happen. On new guns,if its broke. Make them fix it. That's what the warranty is for. I have wasted alot of my own time diagnosing problems on guns to find a broken part that they had to replace.