Need gas system help

jmt686 · June 09, 2007, 12:00

I picked up a Century inch pattern R1A1 for a song a while back, and found out why at the range. The bloody thing won't run. It would try to cycle with the gas system totally closed but couldn't run with more than 13 rounds in the mag.

Upon further research, I opened the feed rails to match the mag feed lips. This meant filing about 1/8" off each side. The angry beavers had only put in the outer return spring, so I ordered a spring set and made it right. Smoothed the bolt carrier rails in the receiver. Tried numerous other tricks I read about here.

With the new springs, there isn't enough gas to run it. So I took out the inner spring and tried again. Now with the regulator set to 1 (0 is fully closed) it will run with a full magazine. However, I don't like running the system with less spring buffering than it was designed for.

The piston will slide in the tube w/out binding. The bolt and carrier will slide in the receiver just by tilting it. The moving parts have a good application of lube.

At the front end, the inside of the handguard looks like the inside of a mousegun upper. Lots of carbon buildup. The gas regulator is also filthy, and the piston seems a bit too loose in the gas tube. The tube is somewhat loose in the gas block even with a hand-fitted pin.

At this point I am thinking of replacing the gas plug, gas tube, regulator, and piston. I may go so far as to have my 'smith make a piston so we can turn it to match the gas tube with minimum tolerances.

What else should I be looking for? Should I consider replacing the gas block or silver-soldering the gas tube as well? I've read and searched the forums until my eyes crossed but I know I may have missed that one vital piece of information.

This is my first FAL. Even with the money I am spending on parts, I should be able to have it running properly for a fair bit less than the cost of a "new" Century that would most likely need some work as well. Also, the education I am getting in how these rifles work is priceless. I just want my rifle to run and really appreciate any help I can get.

**bykerhd** · June 09, 2007, 12:26

Did you measure the head of your gas piston ?
There is a surprising amount of variance in their dimensions.
You might be able to get one of the vendors like GunThings or GPG to hand pick a larger piston for you. Depends on what you have now. Most seem to run .429 to .430 I think. Something like .4305 or even .431 might work better for you. If it doesn't bind up. But, again, it depends on what you have now.

**Stoney** · June 09, 2007, 13:27

Is the gas tube pin in?

Radio · June 09, 2007, 14:35

The gas regulator is not the cause of this problem. Most typical is a gas tube leak where it meets the gas block, worn threads or the missing gas tube pin as mentioned. You can check this with a temporary (it will shortly disintegrate) application of teflon tape. Next often is a mismatched gas piston to gas tube diameter problem; check this with the appropriate instruments. Next in line would be the gas plug, which you can also check with teflon tape. It's theoretically possible to have gas leakage past the front sight, although I've never heard of it. The job of the regulator is to RELEASE gas in a controlled fashion. It would only need replacement if it was too tight and not allowing gas to escape, or allow adjustment.

--Radio

June 09, 2007, 12:00	#1
jmt686 Registered FALaholic #: 24182 Join Date: Jan 2007 Posts: 2	Need gas system help I picked up a Century inch pattern R1A1 for a song a while back, and found out why at the range. The bloody thing won't run. It would try to cycle with the gas system totally closed but couldn't run with more than 13 rounds in the mag. Upon further research, I opened the feed rails to match the mag feed lips. This meant filing about 1/8" off each side. The angry beavers had only put in the outer return spring, so I ordered a spring set and made it right. Smoothed the bolt carrier rails in the receiver. Tried numerous other tricks I read about here. With the new springs, there isn't enough gas to run it. So I took out the inner spring and tried again. Now with the regulator set to 1 (0 is fully closed) it will run with a full magazine. However, I don't like running the system with less spring buffering than it was designed for. The piston will slide in the tube w/out binding. The bolt and carrier will slide in the receiver just by tilting it. The moving parts have a good application of lube. At the front end, the inside of the handguard looks like the inside of a mousegun upper. Lots of carbon buildup. The gas regulator is also filthy, and the piston seems a bit too loose in the gas tube. The tube is somewhat loose in the gas block even with a hand-fitted pin. At this point I am thinking of replacing the gas plug, gas tube, regulator, and piston. I may go so far as to have my 'smith make a piston so we can turn it to match the gas tube with minimum tolerances. What else should I be looking for? Should I consider replacing the gas block or silver-soldering the gas tube as well? I've read and searched the forums until my eyes crossed but I know I may have missed that one vital piece of information. This is my first FAL. Even with the money I am spending on parts, I should be able to have it running properly for a fair bit less than the cost of a "new" Century that would most likely need some work as well. Also, the education I am getting in how these rifles work is priceless. I just want my rifle to run and really appreciate any help I can get.

June 09, 2007, 13:27	#3
Stoney Former 0311 Contributor Bronze Contributor FALaholic #: 1205 Join Date: Oct 2000 Location: Brush Prairie, WA USA Posts: 3,331	Is the gas tube pin in? __________________ Stoney Bureaucracy,, taking the fun out of life one stupid rule at a time,,,, Old Viking saying: Never be more then two steps from your weapon Don't pick a fight with an old man. If he is too old to fight, he'll just kill you. Peace is that brief glorious moment in history when everybody stands around reloading. - Thomas Jefferson

June 09, 2007, 14:35	#4
Radio Registered FALaholic #: 263 Join Date: Jul 2000 Location: Eastern Washington State Posts: 9,868	The gas regulator is not the cause of this problem. Most typical is a gas tube leak where it meets the gas block, worn threads or the missing gas tube pin as mentioned. You can check this with a temporary (it will shortly disintegrate) application of teflon tape. Next often is a mismatched gas piston to gas tube diameter problem; check this with the appropriate instruments. Next in line would be the gas plug, which you can also check with teflon tape. It's theoretically possible to have gas leakage past the front sight, although I've never heard of it. The job of the regulator is to RELEASE gas in a controlled fashion. It would only need replacement if it was too tight and not allowing gas to escape, or allow adjustment. --Radio __________________ Train Like You Fight: Second PLace is NOT an Option. --E.M. (Ted) Dannemiller II* "You seem to fantasize about me a lot. Maybe you should tell your boyfriend? He could dress up like me or something." --*K.O.A.M.*, November 9th, 2009 "You're better off hoping she don't miss, it's quicker that way." --ce, December 15, 2009

Thread Tools
Show Printable Version Email this Page
Display Modes
Switch to Linear Mode Hybrid Mode Switch to Threaded Mode

June 09, 2007, 12:26	#2
bykerhd Dinosaur Bronze Contributor FALaholic #: 2798 Join Date: Mar 2001 Location: Burlington Vermont area Posts: 13,262	Did you measure the head of your gas piston ? There is a surprising amount of variance in their dimensions. You might be able to get one of the vendors like GunThings or GPG to hand pick a larger piston for you. Depends on what you have now. Most seem to run .429 to .430 I think. Something like .4305 or even .431 might work better for you. If it doesn't bind up. But, again, it depends on what you have now.