16" carbine problem...

CRShooter32 · August 29, 2005, 13:05

I had a fun morning, took the FAL carbine out for her shakedown run. First, I love this little blaster, I found it to be quite accurate, recoil was a little heavier than the L1A1, it felt good really, overall, just a sweet little rifle.

But, I had cycling problems, had the gas turned all the way to 1 to get it to cycle with SA, and 2 to cycle with Aussie, but it short cycled enough to prevent the bolt hold from engaging on the last round. Got her home, came here, read over another post (started by Markypoos), got some ideas as to what the problem might be, and checked my gas system. The Tapco piston had carbon fouling all down the shaft, as if alot of the gas was blowing past it, and it did not move freely in the tube. I pulled the spring off the piston, dropped it down the tube, it stuck fast right, the end did not drop down through the port in the upper. Next, I got the piston out, tapped out the retainer pin, and turned the tube out another half turn, then dropped the piston in again, still stuck, but was able to push it down with the pin punch. Grabbed the original R1, and the old L1A1 pistons, gave them each a try. The R1 piston also stuck, while the L1A1 piston dropped freely. Turned the tube all the way back in, turning it out just enough for it to have a little play, then dropped the L1A1 piston back in, it stuck, gave the tube a 1/2 turn out, the piston dropped free down into the reciever. Repinned the tube, replaced the spring on the L1A1 piston, dropped it in, used the R1 piston to push down, the L1A1 piston moved freely, whereas the R1 and Tapco pistons bound up. Shortened the L1A1 piston the same length as the R1 piston, and am using that for now. The Tapco piston was not used as a compliance part, I still have 7(reciever, barrel, mag floor plates, followers, hammer, pistol grip, and ARS replica short combo device) on the carbine.

The tube on the carbine is an L1A1 tube, the original was all but destroyed when I took it off for the first cleaning, the angry beaver who installed it had it overly tight, and I had to use pliers to remove it. Hopefully, the problem is taken care of, I'm going to try, weather permitting, to get back out tomorrow morning, and run some more Aussie through her.

Farmer from Hell · August 29, 2005, 13:27

Take off the recoil sping and inspect it and the tube. The tube should be nice and bright. De-gunk and relube the spring. If the inside of the tube isnt mirror bright wrap some steel wool on a cleaning rod, chuck it in a hand drill, and give it a whirl up the tube. An old bore brush or proper size my suffice in place of steel wool.

Kind of sounds like you've got a bad gas tube if I read you post right. Like there is a ding or kink in it. Try rolling it on a flat surface and look for abnormalities.

FfH

Sig220 · August 29, 2005, 14:49

When all that checks out and you still have problems, check the size of your gas port.

Some shorter barrels will need a bigger port to get the gas right. Just be careful when you open it up, stay small cause you can't add it back!! Also remember to protect your bore when using a drill bit there....don't want to dig into the opposite side!!!

FAL guy · August 29, 2005, 15:27

If your pistons are verified to be straight, you have a dent or ding in your gas tube. How far in does the piston stop. Is it near the vent holes? This is a common problem caused when some hamfisted goober turns the gas tube in or out with a punch stuck in the vent holes.

cessna-pilot · August 29, 2005, 15:57

I second what Sig220 said, I had the same problem on a G-1 kit before.....
But like he said, only go up one size then try it again....you over do it, and now you got problems...

**bykerhd** · August 29, 2005, 16:15

Gas tubes are pretty flimsy at the end due to the two cuts. The ends can be flared back out slightly using a tool with a taper like a line-up tool or a punch. Doesn't take much to do and you only want to open it back up, so go easy. It sounds like your gas piston is somewhat undersize, or, at least undersize for that gas tube. .429-.430 are the usual numbers quoted for FAL pistons. I've had the best luck with pistons running .4305 to .431, when I can find them.

CRShooter32 · August 30, 2005, 10:49

I checked everything out, and it's come down to the gas port needing to be reamed. Took the carbine back out this morning, and had the same problems, so, I'm going to ream the port on my next day off, and try it again.

CRShooter32 · August 30, 2005, 15:51

Another quick thought to the problem, after reading yet another recent post, I also replaced the recoil springs with Tapco units, they are in fact, stiffer than the original spring set, the piston spring was also replaced with a Tapco unit. I'm going to try the original springs before opening the gas port further, it was reamed once, to 1/8 (.125") when the barrel was cut.

FAL guy · August 30, 2005, 16:08

I hate to beat a dead horse here, but if the piston does not slide freely in the gas tube when inserted with out the spring, the gas port is not your only problem.

CRShooter32 · August 30, 2005, 16:23

Quote:

Originally posted by FAL guy
I hate to beat a dead horse here, but if the piston does not slide freely in the gas tube when inserted with out the spring, the gas port is not your only problem.

I am going to get a new gas tube as well, the L1A1 piston slides freely, it's the Tapco units, and the beat up R1 piston that binds. But I'm going to cover that base as well.

August 29, 2005, 13:05	#1
CRShooter32 Registered FALaholic #: 11071 Join Date: Jun 2003 Location: Pa. Posts: 2,560	16" carbine problem... I had a fun morning, took the FAL carbine out for her shakedown run. First, I love this little blaster, I found it to be quite accurate, recoil was a little heavier than the L1A1, it felt good really, overall, just a sweet little rifle. But, I had cycling problems, had the gas turned all the way to 1 to get it to cycle with SA, and 2 to cycle with Aussie, but it short cycled enough to prevent the bolt hold from engaging on the last round. Got her home, came here, read over another post (started by Markypoos), got some ideas as to what the problem might be, and checked my gas system. The Tapco piston had carbon fouling all down the shaft, as if alot of the gas was blowing past it, and it did not move freely in the tube. I pulled the spring off the piston, dropped it down the tube, it stuck fast right, the end did not drop down through the port in the upper. Next, I got the piston out, tapped out the retainer pin, and turned the tube out another half turn, then dropped the piston in again, still stuck, but was able to push it down with the pin punch. Grabbed the original R1, and the old L1A1 pistons, gave them each a try. The R1 piston also stuck, while the L1A1 piston dropped freely. Turned the tube all the way back in, turning it out just enough for it to have a little play, then dropped the L1A1 piston back in, it stuck, gave the tube a 1/2 turn out, the piston dropped free down into the reciever. Repinned the tube, replaced the spring on the L1A1 piston, dropped it in, used the R1 piston to push down, the L1A1 piston moved freely, whereas the R1 and Tapco pistons bound up. Shortened the L1A1 piston the same length as the R1 piston, and am using that for now. The Tapco piston was not used as a compliance part, I still have 7(reciever, barrel, mag floor plates, followers, hammer, pistol grip, and ARS replica short combo device) on the carbine. The tube on the carbine is an L1A1 tube, the original was all but destroyed when I took it off for the first cleaning, the angry beaver who installed it had it overly tight, and I had to use pliers to remove it. Hopefully, the problem is taken care of, I'm going to try, weather permitting, to get back out tomorrow morning, and run some more Aussie through her. __________________ Joe

August 29, 2005, 13:27	#2
Farmer from Hell Registered FALaholic #: 171 Join Date: Jul 2000 Location: The "free" state Maryland Posts: 1,751	Take off the recoil sping and inspect it and the tube. The tube should be nice and bright. De-gunk and relube the spring. If the inside of the tube isnt mirror bright wrap some steel wool on a cleaning rod, chuck it in a hand drill, and give it a whirl up the tube. An old bore brush or proper size my suffice in place of steel wool. Kind of sounds like you've got a bad gas tube if I read you post right. Like there is a ding or kink in it. Try rolling it on a flat surface and look for abnormalities. FfH __________________ Its good to be alive and not crappin in a bag. Anthony Bourdain Nothing says "Obey Me" like a bloody head on a fence post. Stewie Griffin "Family Guy" The trouble with the world is that everybody in it is about three drinks behind. Humphrey Bogart Mason Dixon FAL Collectors Association

August 30, 2005, 10:49	#7
CRShooter32 Registered FALaholic #: 11071 Join Date: Jun 2003 Location: Pa. Posts: 2,560	I checked everything out, and it's come down to the gas port needing to be reamed. Took the carbine back out this morning, and had the same problems, so, I'm going to ream the port on my next day off, and try it again. __________________ Joe

August 30, 2005, 15:51	#8
CRShooter32 Registered FALaholic #: 11071 Join Date: Jun 2003 Location: Pa. Posts: 2,560	Another quick thought to the problem, after reading yet another recent post, I also replaced the recoil springs with Tapco units, they are in fact, stiffer than the original spring set, the piston spring was also replaced with a Tapco unit. I'm going to try the original springs before opening the gas port further, it was reamed once, to 1/8 (.125") when the barrel was cut. __________________ Joe

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August 29, 2005, 14:49	#3
Sig220 Registered FALaholic #: 11622 Join Date: Aug 2003 Location: SE Texas Posts: 4,869	When all that checks out and you still have problems, check the size of your gas port. Some shorter barrels will need a bigger port to get the gas right. Just be careful when you open it up, stay small cause you can't add it back!! Also remember to protect your bore when using a drill bit there....don't want to dig into the opposite side!!!

August 29, 2005, 15:27	#4
FAL guy Registered FALaholic #: 4319 Join Date: Oct 2001 Location: Oklahoma City Posts: 2,142	If your pistons are verified to be straight, you have a dent or ding in your gas tube. How far in does the piston stop. Is it near the vent holes? This is a common problem caused when some hamfisted goober turns the gas tube in or out with a punch stuck in the vent holes.

August 29, 2005, 15:57	#5
cessna-pilot Registered FALaholic #: 7770 Join Date: Oct 2002 Location: St Louis, MO Posts: 424	I second what Sig220 said, I had the same problem on a G-1 kit before..... But like he said, only go up one size then try it again....you over do it, and now you got problems...

August 29, 2005, 16:15	#6
bykerhd Dinosaur Bronze Contributor FALaholic #: 2798 Join Date: Mar 2001 Location: Burlington Vermont area Posts: 13,262	Gas tubes are pretty flimsy at the end due to the two cuts. The ends can be flared back out slightly using a tool with a taper like a line-up tool or a punch. Doesn't take much to do and you only want to open it back up, so go easy. It sounds like your gas piston is somewhat undersize, or, at least undersize for that gas tube. .429-.430 are the usual numbers quoted for FAL pistons. I've had the best luck with pistons running .4305 to .431, when I can find them.

August 30, 2005, 16:08	#9
FAL guy Registered FALaholic #: 4319 Join Date: Oct 2001 Location: Oklahoma City Posts: 2,142	I hate to beat a dead horse here, but if the piston does not slide freely in the gas tube when inserted with out the spring, the gas port is not your only problem.