Thermold 30 round mags - junk or did I get a bad batch?

I have 10 of the 30 round mags. For the money, I have always thought thery were nice mags. Have never had a problem with any of them.

I used to use them in my first AR that I got rid of after obama took office. I didnt have any problems at all with them. I was told they had military contracts for use in cold environments. When I got back into AR shooting recently I ended up with P mags because everywhere i went they were sold and had great pricing. The P mags simply are Magpuls interpretation of a thermold.