I know this isn't the best pic, but I took about eight of them and this one came out the best.  I picked up this USP .40 about 4 years ago from a pawn shop.  I've handled several other USPs since then, and all of them had a slightly different mag release.  Mine is sort of a sharp triangle shape, while the others were much more rounded, and perhaps a tiny bit shorter.

I'm wondering if my mag release is an aftermarket add-on, or if HK has switched around the design a little bit through the years.  Mine has a VERY crisp letoff, which makes for quicker mag changes.  I like it a lot better than the other USPs I've handled.

Anybody have an answer on this one?

there is an aftermarket mag release for HK?

I'm willing to bet that HK just changed the shape at some point.  I don't think that anyone has made any aftermarket mag release for the USP.

You can count the aftermarket parts out there for H&Ks on one hand & have fingers left over, IMO.

Looks the same as mine. '93 manufacture.

Same as my Tac, AA date code and Compact, AD date code.

HK did change the shape of the mag release at some time, IIRC either 95 (KF) or 96 (KG).  They made it smaller so it would be less likely to release the mag accidentally.