Man… I’m seriously wondering about the gas tube in my case.
I know I was doubtful about the tube being problematic… but my NEW gas tube is .010" fatter at the key end of the tube. Twice the difference of the used rifle tube I had on my bench.
I’m really curious to see if this makes a difference.
A worn out gas tube is a legit cause of short stroking.
This one has less than 1500 rounds on it. I think it NEVER had the bulb end on the tube…
But I’m keeping an eye on the new tube to see if the key is eating it up. The BCG moves freely, and it appears to line up nicely. I can’t wait to shoot the gun again.
demigod, that one’s worn. I’ve seen them come without the relief cut too. If you pull yours you should be able to see if the key is hitting one side more than another.
Tweak…
I pulled the OLD tube out and there was no sign of wear on one side or the other like most of my ARs. It was even all the way around. Either the key ate the hole tube evenly in 1200-1500 rounds, or it never had the step up on the end of it.
I’m going to watch the new tube closely.
that would be a good indicator that it never had the cut.
markm,
I will get you a shipping address tomorrow.
It may be fixed. I might head out to Rio Salado Sportsmans and shot a few mags through it… I mean… .010" leak at the key has got to be a problem.
You can just look at the old tube and say… “that’s not right”. The new tube matches the measurements on Tweak’s diagram exactly. We’ll see.
I’ll try to get a pic of the funky tube today.
It is a total problem, I have this gas tube that is worth a ton of money because it is made from inconel, well since it was a one off the end going into the carrier didn’t have the head like shape which relieves and helps for a not perfect alignment, I was having issues and instead of putting that geometry in I kept removing some of the tube od. I then further screwed myself because I had to port the hell out of the gun to make it “normal” again.
So I did learn from it that if you had a way overgassed gun, and for some reason you couldn’t fight it with buffers, springs, you could kill some power at the connection with the tube.
Well it was the GAS TUBE, boys! I ran out to the square range after work and ran several flavors of ammo through it… and re zeroed it.
Last 20 rounds was PMC bronze shot 2 at a time for a bunch of lock back checks. The gun ran everything great. I could FEEL that it was cycling right.
Very interesting learning experience. :eek:
Or you just install an adjustable gas block instead of cobblefucking.
Yeah… intentionally creating this problem doesn’t warm the heart.
Mark, was this problem with the gas tube on your BCM 14.5"?
Yep! I’m puzzled about it because the gun ran buffers that were WAY heavier than appropriate for the set up in the beginning…
So either the key wore out the tube, the tube never was in spec… or the tube was just softer steel. There were no signs of binding… the carrier moves like glass in the upper.
I’m going to run it like crazy for a few months and watch the new tube.
That’s interesting. I’m glad it’s fixed and I’ll be interested to see how it performs over the next couple thousand rounds. I’m going to take a look at me in a few. I don’t have any problems, I’m just curious if they used a different tube at one point.
Thanks buddy.
I should get a pic of the old tube… just haven’t got around to it. It looks like there never was a step up on the end of it…
And there’s gas fouling from the leakage all over it.
I should give one a try but something tells me I will kill it or it won’t function after getting red hot. Easy enough to try but I just don’t see it working out for my case, for most yes,(but I am going to get one now that I have thought about it, buffers usually do what I need but its way faster to turn a setting than remember parts). With the ammo variations between good and bad that I shoot, that’s one of the real draws for a piston setup, I usually port out the silencer setting as I don’t shoot suppressed that much.
Here is a new one I just experienced, yesterday I was using a piston setup and it started dying, found a washer in the chamber, found the rollercam in pieces, didn’t see anything wrong, replaced rollercam, 50 rds later same thing, upon further inspection I broke the bottom tooth on the barrel extension, that’s a first for me, and it did last about 25K.
So I pulled out an AR, knocked out a few hundred rounds perfectly, I pulled it out this evening and within 60 rounds the gas tube was connected to the carrier, I guess the roll pin failed and let the tube go, the gun couldn’t cycle all the way rearward. A roll pin is a pretty easy fix although I am sure the tube needs a little tweaking after that and I may as well put a new one in.