Maybe someone here can help me. Just traded for an AR15 upper. It'a a 16" bull barrel (believe a Wilson) don't know who's upper it is. Well here's the problem, Has a Free Float tube and every time you fire it you get a blast of gas in the face. The tube was 12.5 inche long and extended way past the gas block. Thought I would shorten it to see if that would help, it's now 9.5" long and is almost even with the gas block. It cycles every time, I have put about 80 rounds thru it and it was not new when I received it. Now some gas leakage may be normal but it should not make your eyes water. I would ahve figured that if it was a major gas leak it would not cycle but that OK. Should I pull off the gas block?? What should I check?? Anyone have this happen and know of a fix??
Thanks in advance.

Is this your first AR ? Gas in the face is a "feature" of the AR15 direct gas impingement system. If the rifle is cycling OK, there is probably nothing wrong. If the blast of gas is a big deal for you, a gas buster cocking handle will reduce the amount of gas blown back from the receiver (the usual culprit). I'm not sure how the gas could be getting all the way back from the gas block to your face, free float tube or not, other than through the usual upper receiver/bolt carrier route.

ETA: Are you shooting Wolf ammo ? If so, this is unusually unpleasant as the gas stinks more than usual and tends to make the eyes water a lot. Try a different brand of ammo.

No, this is my third, (if you don't count what Uncle Sam issued). The other two are 24" and 20" barrels and this is a 16". The 24 is also a free float tube, the 20" has standad hand guards. Maybe it is just because the block is so much closer then on the others. Maybe if I tried blocking the holes in the ring on the side where my face is? Are there better FF Tubes out there that make this less of an issue?

Are you sure that the gas is coming from the gas block and not from the back of the charging handle? Us highpower shooters that get gas in the eye usually get it from the back of the charging handle. There is a very easy and cheap fix for this if this is the area.