I recently purchased a new colt socom 2 and took it to an outdoor range. I was was using Winchester 5.56 white box rounds, and the rifle functioned normally for the first 8 rounds and then failed to feed after firing a round with sometimes not peeling the round at all and sometimes a jam with the primer end of the bullet still in the mag. I tried 3 different mags and spent the rest of the day single shot mode. I cleaned the gun and took it out again using Remington 223 rounds, and the same scenario resulted first ten rounds fine and then ftf. The interesting part on this day is that after a failure i would run a bore snake through the barrel amd get 4-5 normal operations before another ftf and this was considtent through 15 bore snake cleanings. I thourghly inspected the gun no loose gas key no buffer spring interferences and othe the other symptoms of short cycling. I went to the range again changing the lubricant to clp from hoppes gun oil, the gun went 20 rounds this time before FTf. I loaded two clips with two rounds and the bolt would lock open after the last round. The rest of the day ftf was intermittent sometimes it would jam but for the most part it wouldn't peel the round and at the end of the day the bolt wouldn't lock open. I was sighting in the guns firing three rounds and then walking down the outdoor range in 21 degree weather. Is it possible the cold weather is causing this problem or am I missing something that is causing this. The other thing I am seeing in this gun is a lot of copper fouling in the barrel.

Thanks
Phantom