View Full Version : FTE.. Should I drill port or replace piston/tube

April 01, 2002, 12:16
Went campin with the G1 this weekend. Good new is that it didn't blow up in my face. Bad news is it fails to extract.
Gas lug is set to A.
Tried all gas setting.
Bolt carrier only goes back about half way and then rechambers the fired round.
Fired Shells extract fine when hand cycling.
Carbon deposits visible on piston right up to the last lobe.
Recoil springs lightly lubed and clean.
Bolt/bolt carrier do not bind.
Piston does not bind, but a little loose.
Gas tube pinned but slightly loose. Will use teflon tape in the future.
Didn't measure the piston or port yet, no MIC.

Any suggestions? Drill the port? Replace piston/gas tube?

April 01, 2002, 12:58
Stay away from the teflon tape. Just helped a friend fix his century POS. They used teflon on a crappy gas tube. The teflon got into the gas tube and jammed up the piston. Call Tapco and get a new gas tube for $20. Make sure the gas piston is not undersized. Put the proper pin in the gas tube, a hanger is supposed to be the correct size.

Roll the piston on a flat surface and see if it is bent.

My G1 build didn't want to cycle for about 20 rounds then it started running right. Could have been crud in the gas port or just tight parts getting acquainted.

Might want to clean and polish the chamber.

April 01, 2002, 20:13
I had the same problem and was comtemplating the same ideas you are discussing here with my first G1 build.

I got a lot of knowledgeable help from some very kind and considerate people and completed the build with Great Personal Satisfaction. I have included the thread for your review.

Good Luck!

April 01, 2002, 22:13
FTF FTX FTE checklist (http://www.falfiles.com/cgi-bin/forums/ultimatebb.cgi?ubb=get_topic&f=3&t=002574)

Do you know the size of your gas port?

April 02, 2002, 22:49
I had a FTE on my G1. Shot 30 rounds. No eject, no lock back, no feed.

I measured the gas piston OD and the gas tube ID. Bought new gas piston and gas tube. Set gas setting to 1. Fired 20 rounds. Same problem, FTE.

Carefully flared the end of my gas tube to "seal" the threads. Shot 35 rounds. Same problem, FTE.

Carefully stoned and smoothed the park on the carrier, bolt, and the inside of the reciever. Shot 20 rounds. Same problem, FTE.

Drilled the gas port out to 7/64". Shot 2 rounds. Ejects fine, locks open fine, feeds fine on a gas setting of 5. Then I shot another 40 rounds. Throughly enjoyed myself.

My suggestion. Skip all the agrivation. Drill the port and be done with it.

April 02, 2002, 23:18
I have had the same problems with a G1 build.
Cleaned the recoil spring and tube , then lightly oiled.
Measured the gas plug - 0.430".
Measured the gas piston - 0.430".
Measured the gas port - 0.096".
Only the last 3 rounds will eject from the magazine, with only the last one ejecting some distance.
The bolt and carrier slide loosely in the receiver.
The gas piston moves freely.

My speculation is that the gas adjustment nut fits too loosely on the gas block. I'm not sure what these are supposed to measure, but the only way I can think of to do anything about this is to paint the inside of the nut and/or the gas block with a high heat paint to reduce the clearance.

Instead I drilled the gas port at 0.104", and will see how this works. I'm sure that FN drilled them at 0.096" for a reason. It just seems that the rifle should function like it is. :confused:

April 02, 2002, 23:27
These rifles probably worked fine with a .096 port when everything was brand new from a sole-source factory.

Nowadays, the gas blocks all leak at the joint between the block and the tube. The pistons and tubes are mismatched. There is all kinds of stacking of tolerances happening. I've been .109 and guilt-free for months now.

April 03, 2002, 12:36
OK, Drilling it is. One more question thought. I know that the nominal diameter of a new unmodified gas port is aprox 0.097"
I'll open it up with a 7/64" drill bit which is 0.109". But what type of bit do I need to avoid snapping it in the port?

April 03, 2002, 14:02
Use a NEW bit.

The silver-colored "carbide" bits do very well. The blue steel bits DO NOT cut FAL barrel.

Your new bit should do the job in less than 5 seconds. Preferably use a regular hand-drill motor. For some reason, the faster RPM Dremel does not work as effeciently.

April 03, 2002, 14:20
Originally posted by gary.jeter:
<STRONG>Use a NEW bit.
.... For some reason, the faster RPM Dremel does not work as effeciently.</STRONG>

And I bet that kills you Gary :)

I'm just waiting for the post someday that you performed an emergency tracheotomy with a cordless dremel.

April 03, 2002, 14:28
I did slash my hand real good on a burr on the cocking tube of a CETME. I used the Dremel to debride the wound.

April 03, 2002, 14:36
Originally posted by gary.jeter:
<STRONG>I did slash my hand real good on a burr on the cocking tube of a CETME. I used the Dremel to debride the wound.</STRONG>

I'm pretty sure that if you worked enough with the metal cutting bit you could cauterize the wound.

April 03, 2002, 14:37
Thanks for the help Gary.

PS The woman got me a dremmel for my B-day, EXCELLENT! Almost as versitile as duct tape!

April 04, 2002, 16:22
UPDATE: Picked up a couple Titanium 7/64" bits from the Depot today. Calling in sick tommorrow & will get started.

Advice on protecting bore and avoiding burrs. How about a cleaning rod or bullet (unfired of course) in the barrel behind the port?

Too lazy to search the threads, anyone know any about drilling ports?

April 04, 2002, 17:37
You could stick a wood dowl down the bore for added protection. Run a patch thru to get the burrs out. Blast away.


April 05, 2002, 08:18
I might be a little late, but I'll add my 0.01 anyhow. Drilling the gas port should really be the last thing you do after going over the rest of the rifle with a fine tooth comb:

Does piston drop freely through the gas tube with the bolt, carrier, and piston spring removed?

Do the bolt and carrier slide fore and aft smoothly with no binding or grating?

Is your recoil tube packed with grease? It should be clean, smooth, and lightly oiled.

Are you lubricating your rifle with grease? Grease causes sluggish cycling in my FALs. They run great with a light coat of oil. This is particularly true when lubing the carrier and receiver rails.

Is your chamber smooth and free of burrs or rough spots? Are your cases scratched? Chuck up a clean 50 cal bore mop and polish your chamber with some JB bore paste or equivalent.

If your gas tube is loose in the gas block just get a new one from DSA. Measure your piston and replace with a DSA if undersized.

Do you have a lot of carbon on the barrel in front or behind the gas block? That indicates a leaky gas block. Not sure if lock-tite is advised here or not. Might just go ahead and drill the port instead of trying to fix this leak.

You might be leaking gas from around the gas plug. You could try a new plug but it could be a worn gas block. Time to drill the port or replace the gas block/plug (I'd be drilling).

If all the above items check out OK then I'd drill the port.


April 05, 2002, 22:58
Too late Byron!
Already checked all of them, all fine. Drilled the port this morning. Took all of 20 minutes. 7/64" titanium bit cut like butter. Will hit "my range" on Sunday to test her out, but I'm confident that she'll be fine. Also painted the numbers on the sight with insignia white while it was off.

Jeter, another dremel use: pencil eraser screwed onto the end of the threaded polishing shank. Took off the excess paint in no time. Again proving that the dremel is almost as versitile as duct tape!

Again, thanks for all the advice guys.