Over gassed FAL

[Visceral_Malice]

Hey guys. New to the forum and I have a question I have been unable to answer for months now after continuous search. I picked up a CAI FAL about 6 months ago because I got a damned good deal on it. Its one of the full metric ones built on a G1 kit. Anyway I'm pretty sure my bolt is being over gassed because it will always lock back no matter what setting I have the regulator on. I know its not a big deal because it functions, but I also know that it shouldn't be locking back on the 1 setting. My first thought was the springs were old and needed to be swapped, so I did that to no avail. They did, however, need to be swapped. My next thought was the piston was the issue. I was having issues with my piston not freely falling through the gas tube, so I bought a new one and the results were the same. Next idea was the gas tube. I took it off and did a thorough inspection, but when I reassembled it, the piston slid through it beautifully. I took it to the range and still had the same issue though.

Now I'm pretty much stumped. My only thoughts are the barrel has gas ports that are too large or something is up with my gas block. Any help you guys can provide me would be greatly appreciated as I'm at wits end with this problem. One positive thing is I'm ready to buy a kit and assemble it myself now as I've had to pretty much strip this thing down all the way.

[Redleg]

If your bolt is locking back after each shot it means the bolt hold open device is engaging and has nothing to do with your gas settings. Either you have fired the last round in the magazine or the magazine is defective and allowing the BHO to engage or the bolt is catching on the the rear lips of the magazine which hold the rounds in the magazine.

[falister]

Hi, a lot of these parts guns have this problem, you are over gassed. With a L1A1 gas block you are stuck but with a metric gas block you can try this, unscrew the regulator another full turn. To make this a little clearer undo the regulator down to 1 like you have done but keep going 1 complete turn further and then try the same test. The numbers on the regulator will line up the same only one turn further back, barely a millimeter (.040"), set the regulator at 1 and it should not hold open on the last shot. If it does the gas hole in your barrel needs to be reduced but the procedure above usually fixes this. If it does not hold open (which is good) then move regulator a click at a time until it does lock back on the last shot, the move it 2 more clicks for reliability and you're done. Let us know how it goes.

[Visceral_Malice]

Thank you falister for being the first person to actually understand the problem. I have asked this question a few other places and can't get anyone to understand the issue. I have backed the regulator all the way out until the port on it is wide open. There is zero part of the regulator obstructing it and I'm still getting bho. I'm assuming its the gas ports on my barrel then. Is there any kind of doable fix for this or should I just pick up a new barrel?

[SgtStrykerUSMC43]

Thank you falister for being the first person to actually understand the problem. I have asked this question a few other places and can't get anyone to understand the issue. I have backed the regulator all the way out until the port on it is wide open. There is zero part of the regulator obstructing it and I'm still getting bho. I'm assuming its the gas ports on my barrel then. Is there any kind of doable fix for this or should I just pick up a new barrel?

You wouldn't happen to have a picture of the gun and maybe a close up of the gas block/plug, as viewed from the front of the weapon (installed), would you?

Also, do you have pin gauges?

[Visceral_Malice]

Ugh, I meant I've had it on setting 7 not setting 1. I took quite a few shots of it. Also, no I don't have pin gauges, but I almost bought some a few days ago in plans to do a FAL build soon.

Gas plug


Gas block w/o plug


regulator


another angle


other side

[Darius]

In case this might help:

Position 1: all gases go the gas-piston / maximum blowback:



Position 7: all gasses are bleeded (see the opening at the top of the gas regulator) / minimum blowback:



SOP: Feed the FAL with one cartridge at the time; start at position 7; normally this will cause a "short recoil"; close the gas regulator click by click (from 7 towards 1) until the breech block is held to the rear; now verify if it works reliably for several operations; if there is still a failure to maintain the breech in open position, close the gas regulators by one more click (i.e. lower figure) and test again.

[SgtStrykerUSMC43]

From reading your posts, it appears the gas piston is on the high side of tolerances and the gas tube is on the low side, if the piston is original. If the piston is U.S. mfr. then I would look at the piston as being the culprit. Either way, the platform is very robust and can handle the increased bolt speed. If you're concerned about a battering effect on the recoil plate, I would suggest a buffer from Buffer Technologies. As you shoot the weapon, the gas system will wear, and eventually you will have to reduce the amount of gas being bled off into the atmosphere.

Ugh, I meant I've had it on setting 7 not setting 1. I took quite a few shots of it. Also, no I don't have pin gauges, but I almost bought some a few days ago in plans to do a FAL build soon.

Gas plug


Gas block w/o plug


regulator


another angle


other side

[Visceral_Malice]

Thanks for the help Sgt. I know its not a major problem, but it was just bothering me having my weapon not functioning ideally. I may just pick up a new gas tube as well and go run the hell out of it.

[SgtStrykerUSMC43]

Do you have a means of measuring the OD of the piston accurately?