AR Sponsor
Posted: 2/16/2014 7:45:10 AM EDT
|
I just completed a flurry of AR builds ( 3) and two out of three have no problems. They are feeding and ejecting with no problems. I have built other AR's throughout the years and never really had an issue like I am having now on one of my new rifles. When the rifle is fired, the BCG barely moves back, so obviously no ejecting happens and no stripping of the new round out of the magazine happens. Seems to not be getting any gas?
I immediately thought it’s a gas issue, so I took the gas block off to confirm that the gas tube is installed correctly and there are no obstructions and air is traveling to the gas block with no issues. I realigned the gas block on the barrel and took it out shooting again and same issue. One thing I noticed with the problem rifle is on the gas tube where it goes into the BCG, there is no bulge on the end of it and it’s basically straight. Could this be the problem? I don’t notice any gas leakage at the block at the barrel Things tried so far- Realigned the gas block Confirmed air is getting to the gas block from the tube Switched out the BCG Confirmed the headspace is OK Switched out the buffer and spring Tried different mags and ammo http://i1356.photobucket.com/albums/q721/broomy111/UpdatedAR_zps106152e9.jpg |
|
Check to make sure the gas tube is inserted into the gas block with the gas port in the gas tube facing downward so it properly aligns with the gas port in the barrel. The back end of the gas tube should be flared out slightly like the tube in the pic on the right, I refer to this as the bell, of which the bell helps to create a seal inside the carrier key (gas key). Check to make sure your gas key is tight, and is properly staked to the bolt carrier. Also make sure that your 7 bolt lugs and carrier are wet with some type of gun lube, I prefer Slip2000 Extreme Weapons Lube "EWL", as from the pic it looks dry of which may cause too much friction when a rifle is new. Also for process of elimination, next time you go the test fire it, if it is still having problems, then try swapping out the bolt carrier assembly from a different rifle just to make sure it is not in the bolt carrier or bolt.
CY6 Greg Sullivan "Sully" SLR15 Rifles TheDefensiveEdge.com (763) 712-0123 |
|
Thanks for the response Sully.
I’ve tried three different BCG’s in the rifle to rule things out or in. ( Shadow Ops nickel boron, Young Manufacturing chrome, Windham phosphate) all with Mil-comm grease on the lugs, bolt, and rails and same issue with all three. So it appears to not be BCG problem. All of those BCG’s were taken from working rifles and I did try a second Shadow Ops nickel boron BCG and same issue. When I had the gas block off the other day and when I blow into the gas tube, there was no obstruction and I can feel the air in the gas block. After my last alignment of the block and it didn’t cycle correctly, I just put a piece of a drip system hose on the gas tube in the upper and when I blow on it, I can feel the air coming out in the barrel with no obstructions so it appears the block is lined up correctly which has me even more confused. In the past when I’ve had slight issues like this, it was always a block alignment as the cause. The one thing that is different is that gas tube on the rifle doesn’t have the bell on the gas tube, so would that cause less of a seal to not move the BCG? I usually get YHM black plated gas tubes since they look good under the rails, but this one is from All Star Tactical since at the time I couldn’t find a rifle length one at the time. What drives me crazy is I just helped my father in law order and put together his new rifle and it has the exact parts as this rig and the only difference is the gas tube. He has a YHM one, so that’s my guess is where the issue is. Any other ideas before I order that YHM tube? http://i1356.photobucket.com/albums/q721/broomy111/_DSC5024_zps276dfd34.jpg |
|
That is an obvious defect and the tube should be replaced on general principle.
I have a rifle tube on my desk where the end of the tube is only slightly larger (+.001”) than the body of the tube and about 2” of tube behind the end is noticeably smaller in diameter so it looks like the end is larger than it actually is. My tube looks very much like the pic on the right. The tube I have out is approximately .180” in diameter and .170” in the reduced diameter area. |
|
The tubes are not flared or belled. An area of the tube for a couple inches from the end is reduced in size. The end on every tube I have measured is the same size as the main body of the tube past the reduced portion. I would guess it is reduced in size to ease alignment and binding issues if the full sized tube entered the full length of the key.
I have seen tubes worn down on the end that still functioned but hopefully changing the tube will fix your problem. |
AR Sponsor