I recently purchased an upper from a fellow member, upon close inspection the front section of the gas tube looks like it was chewed up with a pair of plyers. I want to replace it but don't know how. should I send it off to Bush master? Is it an easy job? Do you need any special gas tube wrench for installation or removal? The gas rings on the bolt also have seen better days and need to be replaced, any tips on installing them would also be very helpfull.

Thanks in advanced.  

changing the gas tube is easy--no need to send it back to bushmaster

gas tube: simply get a pair of plyers and and yank the tube towards the reciever; h/w, if its like most used ARs, CLP the area where the tube goes into the FSB/gas block, let it soak as carbon buildup might have cloged the tube area
--if it gets tough to pull out, switch from a pair of pliers to a set of vice grips (line w/ tape if you are worried about scratching the tube), lock it around the tube and pull towards the reciver
--if the vice grips dont work, then w/ the grips still locked onto the tube, get a mallet and smack the grips downwards toward the reciver until the tube gets loose

look to the area for FF tubes: www.ar15.com/forums/topic.html?b=3&f=4&t=226782

gas ring: a knife or sm screwdriver should pry/pop em off at the gaps; CLP clean the exposed areas, and slide the new ones on from the rear of the bolt

Follow ALPHAGHOST's directions to remove the gas tube, but don't forget to drive the gas tube roll pin out first with a 1/16" punch.

1. Remove each gas ring (starting with the rear one) by hooking the ring's gap and lifting the end of the ring up and out of the groove. Then spin it off. Be sure not to pull the rings' ends straight apart -- twist them open.

2. Install the gas rings onto the bolt by winding them on from the rear of the bolt. Offset the gaps in the rings.

Thanks for the great info guys, I've owned AR since I've been 16, but never had the need to rebuild any part of one. I guess who ever had this upper down the road was a bit of a hack. I'll fix her up nice.

Thanks again!

Quoted: Follow ALPHAGHOST's directions to remove the gas tube, but don't forget to drive the gas tube roll pin out first with a 1/16" punch.

oh yea....i forgot about the roll pin

sorry about that undertaker, thanks for the fix m4madness

Great news! Thanks to all of the great help/info from you guys, my A1 carbine upper is a happy camper and so am I. First off let me say that Bush master rocks! I ordered all of the parts I needed and a few other goodies and just over 24 hours latter allong comes the UPS truck with my stuff, all I can say is Hooorraaaaaaaaaaaaaaaaaaa!!!!  Everything worked out exactly as you guys stated above. The gas tube took about 15 mins to replace (soaked it good in CLP over night ) and the gas rings about 5 mins. I also replaced the extractor spring and insert. Next I'm replacing the ejector spring even though it seems to be fine, I figure I'll start out fresh.

Thanks to all for the help

Undertaker out

Quoted: Follow ALPHAGHOST's directions to remove the gas tube, but don't forget to drive the gas tube roll pin out first with a 1/16" punch. h 2. Install the gas rings onto the bolt by winding them on from the rear of the bolt. Offset the gaps in the rings.

Where exactly can I find the "roll pin"?

Quoted: Quoted: Follow ALPHAGHOST's directions to remove the gas tube, but don't forget to drive the gas tube roll pin out first with a 1/16" punch. h 2. Install the gas rings onto the bolt by winding them on from the rear of the bolt. Offset the gaps in the rings. Where exactly can I find the "roll pin"?

Center of the  FSB.

Just out of curiosity, should the gas rings be replaced when the bolt no longer supports the weight of the bolt carrier when stood on end? I have always understood this to be a "guide", but don't know if it is the defacto "when to".

Before I replaced mine (gas rings ) the whole bolt carrier would just slide out of the top of the upper receiver when stood on end, the only thing that would stop the carrier from falling out was the charging handel. Now with the new gas rings installed the bolt is snugly in battery and stays put like it should, even if I hang it upsidedown and shake the upper. You could see my rings were beat to shit so it was kind of a no brainer for me that they needed to be replaced. As long as your at it you may as well replace the extractor spring, I did that and the ejector spring as well.