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Armalite Adjustable Gas Block Help
Silver:
Yes, FTF. Instead of opening up the original tube, I purchased a new Armalite gas tube which I understand has a significantly larger port. I went with the adjustable gas block in case the port is "too large."
On the FTF. Every round ejected fine. Out of 21-24 rounds I had two rounds halfway feed (not sure of the proper term - front half of the round was in the chamber with the lower half still in the mag and the bolt resting up against the side of the round.) All the rest of the rounds remained fully in the mag.
Sounds like shortstroking and as you all said, insufficient gas pressure.
Thanks for the specifics JAK. I suspected something like that but wasn't sure which is which. In the videos I watch of people tuning their gas blocks, they seemed to be loosening (they started with the screw fully or near fully closed) the one on the side through gaps in the handguards.
That said, the allen wrench that came with the gas block is rather long which seems to allow for adjusting the front screw of the gas block as if it were under a good length of handguard.
SS_N_NE:
Because of patents on gas blocks and that Armalite seems to keep the adjusment a secret (guess you would need to contact them for specifics) it seems simpler to try alternately tightening / turning the 1 or 2 screw and realize which one is locking the other. Or, find the one that locks the other in mid turn...that screw is the lock...other is the adjuster. Saw somewhere that Armalite uses a .099 port in their barrel for AR-10. Are you certain the port on the block and barrel are lined up? Could be a very simple but confusing issue. Also ensure the entire gas system is free from any obstructions (silly but simple issue). Carbon from shooting or something from a cleaning (pipe cleaner/ patch/q-tip" in the barrel port, block, gas tube, port even in the gas key). With the adjustment screw backed out the gun should fully cycle. As the adjustment screw is turned in, the felt recoil should be reduced until the gun no longer cycles. I realize that typical instructions are the reverse, but the gun should be set up to cycle with an unrestricted block port. The adjustable block just slows things down by limiting gas to the BCG.
Silver:
Learning can be so embarrassing sometimes. Had the sudden epiphany that the gas port is in the barrel and not the hole in the gas tube lol. Thus, if I need to open up the port a bit, that requires drilling the barrel and not simply drilling the gas tube (or replacing the gas tube with one that had a larger opening).
Duh.
That said, went to the range to try out the new gas block and, another moment of shame, apparently I over tightened one of the bottom set screws on the gas block though I'm not sure how, I really didn't put a lot of twist on them. Now the gas block is like the handguard, free floating. :laugh:
Anywho, back to the drawing board.
shooter:
did you strip out the set screws? yes you need to very slightly open the port in the barrel, if you need I can rethread the gas block for you
SS_N_NE:
Drill bits come in a lot of different sizes...more than increments of 1/64".
OK....why do I bring that up? I am a machinist. I use 115 pc. drill sets, since there are fractional, letter and number bits. Don't just grab a fractional bit and drill out your barrel. First, you want to have an exact size and work in small increments. That is going to require a set of number bits or at least the right size individual bit(s). A second thing to consider is dealing with the bur created when a twist drill goes through steel. In other words there is going to be metal sticking out inside your barrel. Measures have to be taken to ensure the bit can not get across the bore and damage the other side of the barrel. Nicks and burs in a rifle bore can lead to a lot of strange shooting problems. Bur removal and bore inspection are not cheap DIY items inside a gun barrel.
Stripped threads can be drilled up a size and threaded for an oversize setscrew...or thread repaired with a heli-coil or similar thread repair system. The thread repair kits are not especially cheap and should be done in a drill press or milling machine to ensure centered and square drill/threading for the repair threads.
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