12-02-2021, 10:59 PM
bjmac Wrote:Yeah, I already went through it, blew through the gas tube and had flow at the block. Blew through the key with bolt in, no flow. I pulled the bolt blew again and had flow. I like to think I'm pretty good with ar's. The only thing I noticed is the tube doesn't have the normal obvious shoulder at the key end. I checked the fit in the key, it wasn't loose but I've never had the need to check that before so I have no reference and I really don't want to pull any of my others apart to check and mess with accuracy. I didn't see any carbon on the tube near the key like it was leaking back though. I've been dealing with these things for 20 years and this has me stumped. The problem is I can't shoot that often as its an hour drive from home.
There should be a flare or button on the end where the gas tube engages the gas key. The easiest way to check is with a Mark Browns custom gas tube gauge https://www.brownells.com/gunsmith-tools...41043.aspx
This does not mean your rifle will not work since Olympic Arms never used flared gas tubes with their rifles since they had oversized their barrels gas ports compared to most mill spec. The gas key inside diameter should be .180-.182
The gas tube ends should be .180 -.0006
An easy way to check for gas key obstruction is with a piece of weed wacker line. If it pushes through to the inside of the carrier then you're good to go.
If you do a revers torque test on your gas key screws at 30 inch pounds, you can tell if a screw is broke which can be a major cause of gas loss. Most short stroking is related to gas key problems in my experience, besides a clocked gas block to barrel port..
If you have another bolt carrier that is known to work, it is a simple way of testing if it is a carrier problem..