Forum:Barett .50 Cal Extended Mags prob, need help!

Hey, I'm a level 70, 0th prestige on MW2 right now. Unlike in COD4 and WaW, I actually plan on attempting the useless feat of completing all challenges.

Yeah, yeah, blah blah blah, it's not worth it, i know. I just pretty much said that. My aim is to have fun. Not the typical COD addict's I-want-10th-prestige-and-i-want-it-now attitude. So just lend me a hand and spare all the talk. I've had enough from WaW guys already.

So I want to unlock Barett .50 Cal mastery. But for some reason, the Extended Mags challenge is locked at 6/40 penetration kills. The goal's to get 40 kills with bullet penetration with FMJ, right? I'm pretty sure i've gotten plenty of those, but it's stuck at 6 out of 40. Am I doing something wrong?

thanks, Hooz