I just wanted to post some notes on the barrel swapping that I did this afternoon. I am so psyched that I was able to do it myself and just have to tell somebody. My wife just doesn't understand ("That's nice honey, now go cut the lawn").
I've had a XM15-E2S for sometime and I wanted to "spruce" it up a little. I bought a V-Match Upper Assembly and 20" barrel to swap out the current one on the A2 upper.
Although the 20" barrel and my new bolt/carrier assembly have not arrived, the V-Match has so I went ahead and swapped the uppers.
1. Gas Tube Removal - after reading all of the horror stories here about stuck tubes, mine came out without a problem. I was worried when I removed the handguards and saw a some carbon buildup near the front sight. I removed the pin, sprayed a little WD-40 in and worked it a little with a pair of pliers. It came right off.
2. Barrel removal - that was the bitch. There was much more than the spec. 35-40 ft/lbs on that barrel. My first thoughts were, "is this thing reverse-threaded?" but I looked at the new upper and confirmed the threading. I had to give it almost all of my 220lbs on the barrel wrench and it finally came loose.
My 20" barrel and bolt/carrier assembly are in the UPS pipeline so, with any luck, I'll have it all together next weekend.