I am wondering...
 

What kind of mag is this:
It came with my shooter, it's an aftermarket mag with a plastic follower and a plastic bottom. I shot already 500-600 rounds with my Luger and it works great. I had maybe 3-4 times a problem with the last round in the mag standing upright.
I thought maybe it is a Cheaper-than-dirt mag, but those magazines are not reliable, as far I know. This one works great.

THe mag shown appears to be a blued Triple K with a repro aluminum bottom added in place of the original black plastic bottom. The lips appear to be well worn. I have these new with BPB in stock @$25 or the better new MecGars @$35. TH

Tom,
the bottom is a black plastic bottom, not an aluminium bottom.

Tom is correct that this is definitely a Triple-K mag... I think the photos make the black plastic bottom look like it might be made of metal. My experience with these mags are that their quality often varies. You either get a good one... or a lemon. Looks like you have a good one.