Buddy of mine uses these
http://www.ebairsoft.com/magpul-pmag...cs-p-1643.html without issue. He has had them for a year or so. Free shipping as well. They areactually made by STAR if i recall, not Magpul.
They also carry midcaps as well of 120rds but i can't say how good they are. I believe they are the genuine Magpul PMAGS, so i'd imagine they are top notch.