I have fired about 300 rounds though my Micro 9, about 100 of them through a modified Sig 938 7-round magazine. The 938 mag fed various ball ammo with 100% reliability. I found Winchester Ranger 147gr rounds and Speer Gold Dot (uncertain bullet weight) to be unreliable on the 6th and 7th round loaded--basically, the rounds take a nose dive out of the magazine and jam into the feed ramp. I have had 100% reliability firing about 70 rounds of this ammo with the standard 6-round mag that the Micro 9 ships with. Does anyone else have experience with fully loaded Sig 938 mags with similar rounds? Any ideas to solve the problem? I will certainly try Kimber's 7-round mag when available.