USP sometimes-drop-free mags?

[Garrett]

Remember 15 or so years ago when it was a big deal to get "drop free" mags for your Glock? The earlier non-full-metal lined mags were reportedly designed to not drop free when the mag release was hit, so they could be retained. This was not a desirable attribute in our sport, and the later mags that would freely drop from the grip were much preferred.

I've been playing with a USP 40 off and on for a while now, and I find the mags will drop free easily when empty or nearly so, but will stick in the magwell when fully loaded. All of the 16-round mags I've got do this. It's pretty consistent with all of them. So were they designed to do this? Or do I just have a goofy grip on my gun.

[konkapot]

These are the white mags you're talking about? With the black metal basepads? Shot L10 with those for a long time with no problems other than durability.

Those bad boys should always be dropping free. Rigid/brittle plastic and a metal basepad.

Check the sides of your mags for scratches/burrs. Worst case scenario is that you stepped on one and it's no longer square.

They might swell up a little bit when fully loaded, but should still drop.

If you have a jetfunnel maybe check to see if there's some overlap between it and the bottom of the frame.

FY42385

[Garrett]

These are the white mags you're talking about? With the black metal basepads? Shot L10 with those for a long time with no problems other than durability.

Those bad boys should always be dropping free. Rigid/brittle plastic and a metal basepad.

Check the sides of your mags for scratches/burrs. Worst case scenario is that you stepped on one and it's no longer square.

They might swell up a little bit when fully loaded, but should still drop.

If you have a jetfunnel maybe check to see if there's some overlap between it and the bottom of the frame.

White plastic body with black plastic basepads. Two of these are brand new - no chance of having been stepped on. Besides, they all hang up. If it was a bur or an out of square tube, it wouldn't be all of them. On all of them, when loaded, you hit the mag release and they will all pop out maybe 1/2" and then stop.

The Jet funnel might be something for me to check in to. I don't recall if they did this before installing it.

[konkapot]

The jet funnel really should not be the problem, but we're running out of options I guess.

I am 99.9% sure that mine dropped when loaded, but shooting L10 would have meant most of my reloads were with 1-2 rds left.

I thought they all came with metal basepads......at least mine did. Are they aftermarket basepads?

I hope you get it fixed; although as long as they drop free when empty/mostly empty I guess you're still good to go.

Wish I could be of more help.

FY42385

[Garrett]

I was mistaken. They do have metal basepads.

And the jet funnel wasn't to blame. They still hang up with it removed. When I get down between 5 and 7 rounds in the mag, they will drop free. It's consistent with all five of the 16-round mags. I've got a couple of 10-round mags and they drop free whether completely full or empty.

I checked and the mags swell .20" to .30" when loaded.

Not sure what the answer is.

[Mo Hepworth]

wierd....usually mine would fly out....is your mag release returning well enough when released....are there any marks on the mag body? (white mags would show marks from tension easier)...also is the top round getting hung up on anything?

[Mr.Kirk]

Look at the mainspring, It will bind and move forward making contact w/ the magazine. Polishing the contact area helps a little, but replacing or shortening the spring is the way to go.

[Mr.Kirk]

When I installed the magwell I also installed the match trigger. The trigger set up came w/ a different spring. Going back to the original spring solved the problem and didn't seem to effect the trigger. It still sucks.

You might could modify the block that the spring rests on by drilling out a recess maybe 1 or 2mm.