FTF & Stove Piping issues...

[Zorba]

I've already sent a similar message to GT asking his opinion about my magazines, but I just got back from my second range trip with my '40 42 with:

Intermittant FTF and stove piping issues. One magazine is (apparently) factory Mauser, the other is modern (no-name) aftermarket. Similar problems with both. The aftermarket's spring is MUCH stronger than the Mauser's - but has almost no force for the very last round. Both have some hold open problems, esp. the aftermarket.

The other data point here is that I've taken this gun to the range twice now. The first time I only shot about 25-30 rounds - and other than the aftermarket mag failing to hold open 50% of the time, all was well. Today, I shot about 100 rounds, and had these problems intermittently (with both mags). The only thing really consistent was FTF on the last round, again with both mags. Didn't have that problem last time. Perhaps I oiled something that shouldn't have been oiled? Flakes of brass found inside gun when I cleaned it.

Thoughts & opinions?