gas leak at gas block. Need help.

[thenodnarb]

Finally replaced my barrel after "blowing up" the last one with a couple squibs.

My last barrel had a vltor low pro gas block, and the gas tube was a cut down carbine tube(to the pistol location). This time I tried a cheaper YHM block with another cut down carbine tube. Since the YHM has a gas tube hole that is drilled through, I had to plug the back end with a set screw(screwed directly into the gas tube).

I test fired it yesterday and was getting basically no BCG movement. This was with 9.3g of 2200 behind a 168grain hot cor. Previously I was able to cycle with only 6 grains of 2200. I'm using an A2 stock with a carbine buffer spring, and all the weights removed from the A2 buffer. The only thing that has changed from the last setup is the gas block. I tried plugging the chamber with my finger and blowing into the bore. Most of the pressure escapes around the gas block somewhere.

I ordered a pistol length gas tube and its on the way and hopefully it fits my barrel correctly. I'm curious to hear from other people to see if they can think of anything I may be doing wrong. I think I may be leaking gas from where the roll pin goes through the gas block. When I first drilled the hole, I think I may have drilled it slightly too big so the roll pin is really only holding the tube in but not sealing around the hole drilled.

thanks for your patience reading this and any advice you can give.