I previously had a 9mm USP, and as we all know - the 9mm and 40 cal USPs have polymer bodied magazines. And, the polymer USP mags are NOT metal lined (like Glock mags are).

Well, when I had my 9mm fullsize USP years before - I had two 9mm rounds get sandwiched together inside of the mag as I was firing the gun. The polymer body of the mag apparently bulged and let this happen - and all the rounds underneath jumbled around loose in the mag. To clear it, I had to take the bottom of the mag off, and use a cleaning rod to knock the rounds loose. They were sandwiched in there so good it too several hits to get them loose.

I called HK afterwards and had them replace the mag. It never happened again, but I didn't keep the gun long after that. I always wondered if it would happen again. I felt like I couldn't trust the gun anymore. What if that happened again, but in a self defense situation?

Anyone ever had this happen or heard about such an incident before? In fairness - in 10 years time on all sorts of gun forums, I've only ever seen this mentioned one other time. So, it seems uncommon enough. As tempting as it is to get one again, I will always wonder if it would happen to me again if I did.

No 9mm here, but I have a fullsize .40 and I run the heck out of that gun. I probably have 10k rounds through it and have never had a magazine do that.

I would notice my USP .40 mags would appear to "bulge" when fully loaded, but I never did have any malfunctions with it. I didnt have it that long though because I traded it for my SK. I'll buy another one day, not concerned. I do prefer the metal magazines of the USP C and onward though.

Negative,7 fully loaded USP 9 mags here going on 9 years, never a problem.

I never had a problem with mine. I miss that gun.

Zero issues of any sort. .40 USPf 1994 date code.

Never any problems with the 40.  But you sold the gun because of a defective magazine?  Magazines are a disposable item.

I have had a LOT of different handguns over the years. I won't say exactly how many, but it is a lot. Of any handgun I have ever owned, that is the ONLY gun to ever do that to me. EVER.

It is also the only handgun I have ever owned with polymer mags that are NOT metal lined. If it happened once when the gun was only on the second range trip, it isn't a stretch to think that it could happen again with non metal lined mags. So yes, I did sell it.

I decided to buy something else yesterday instead of the USP, though. So, it doesn't matter anymore...

UPS 9mm mags are too metal lined, at least at the feed lips.  Take a magnet to them and see what happens.  In the Jet Funnel mags you can even see the metal insert, and a magnet will sure as heck tell you that there is something magnetic in the feed lip area and the last I checked, polymers were not magnetic.

Yes, but only in the feed lips, not at the rest of the body, which is what I was referring to.