I bought 2 of the US (original) mags and honestly, they don't work well in my UMP conversion. Failure to feed, other issues (though no feed lip problems). I just gave up and went back to HK - they work 100% of the time - expensive but I'm not trying to collect 20 mags for the gun - just need 4-5 I can rely on.
Do the German mags have reinforced lips? I have 10-15 used LEO UMP mags and the only issue I've ever had is the follower/follower spring in one mag. The rest have been great... I don't have any experience with the US mags.
HK-91, HK-93, USC/UMP Conversion, SL8, G36C, HK45, HK45C, VP9, P30L, USPC 9mm, DJ Getz 94, Omega MP5SD, Vector 53, Vector 51, Cetme Sporter, C93, C93 Pistol, TD-415 (416 Clone), GSG9 416C clone.
I would like to revive this and hear from users of the gen2 US UMP mags. I have searched around, and can't find much. Good? Bad? Appreciate your input.
Why U.S. Made Mags vs. German
I picked up four Gen2 U.S. made UMP mags from HKParts.net a number months ago with an eye toward keeping total cost / U.S. parts count in check on my UMP conversion. The U.S. made mags were $50 ea and counted for three U.S. parts needed. Boom . . . done with 922(R) compliance!
If I had gone with the German mags I was looking at $80 each PLUS $20 floor plate and follower kit each ($100 total for each magazine) PLUS a third U.S. made part, most likely a $135 steel trigger.
For me it was $200 worth of U.S. mags vs. $535 for German mags and 922(R) compliance parts.
So you can see why the U.S. made mags were attractive to me.
Good. Upon opening the package the U.S. mags seemed fine. The fit and finish were very nice. But the polymer seemed a little "lighter" than the HK USC mags I was used to. This could simply be a matter of the USC mags being stumpy little things so they seemed denser. Or maybe the U.S UMP mags used a slightly different polymer. I have no idea and I'd never handled German UMP magazines so I have no real basis for proper comparison. But otherwise they seemed plenty sturdy.
Problem. I had unreliable feeding issues the first time I took the UMP conversion out. Usually on the first cartridge loaded manually. After that, the UMP had no problems cycling. Humph! After that first trip to the range, I took a very close look at everything and figured out what was going on:
The U.S. made UMP magazines did not position the cartridge high enough for the USC bolt to reliably strip them out of the feed lips. And we're talking about 1/32" off or so. Take a look at the attached image to see what I'm talking about.
Near as I can tell, the USC bolt has a little extra cut out on the bottom to fit over the USC's barrel feed ramp. The UMP bolt doesn't have this because the UMP barrels don't have a feed ramp. This means there is less meat on the bottom of the USC bolt to catch he cartridge case.
What I don't know is if the U.S. made magazines are out of spec (most likely?) or if this is typical of UMP mags in general (German OR U.S. made) or if my USC was a little out of spec.
Using a Dremel tool with a small, conical pointed grinder bit I gently shaved off the inside of the feed lips until the magazine would position the cartridge at the right height (per primer position) to match the USC. Once the height was set right I used a polishing compound and felt bit to smooth out the inside surface of the feed lips for smoother feeding. Realistically, however, the return spring on the USC is plenty strong enough to strip out the cartridges.
If this seems nuts to you, well, yeah. I get it. But given how the feed lips hold the cartridge you barely have to take off any material. And this only takes a few minutes per magazine. A little at a time, check fitment, and make sure you hit both feed lips evenly.
Why the fix instead of return? I didn't know if the new U.S. mags would have the same problems and I didn't want to deal with returns. Plus if the mags had the same problems I was facing getting the German mags and I didn't want to lay out that kind of money.
So, $10 in Dremel bits and a few minutes of my time was worth it for an other wise easier 922(R) compliance solution and "cheaper" magazines.
Knowing all this would I order the U.S. magazines again?
It would be wonderful if they worked out of the box but I find I really like the U.S. mag option for ealing with the 922(R) compliance, even if I have to do some slight modification.
Last edited by lupinsea; 08-12-2017 at 12:19 AM.
For what its is worth. You can get factory mags significantly cheaper than $80 directly from HK here:
One day Buddah was sitting under a tree.
A knight walked up and said: "You look like a Pig."
Buddah replied: "And you look like a god."
The knight, obviously puzzled asked: "What makes you say that?"
Buddah replied: "My son, we see in others what we see in ourselves."
And why I'm going to modify the Gen 2 US mags instead of send them back.
Plus I'm not sure if the HK UMP mags have the same issue or not. As I mentioned, I noticed the USC bolt (which is reused) has a cut out to fit over the barrel ramp. If the HK mags position the cartridges at the same height the USC bolt might still not consistently feed.
If anyone has any HK UMP mags it would be great to get a comparison photo posted so we can see how they compare!