View Full Version : Maintenance: carbon fouling on gas piston

March 13, 2001, 19:08
After just shooting my new FAL for the first time (one more big woo-hoo!!!) I am having trouble cleaning the gas piston and gas plug to be as shiny as they were before I shot it. Who's got the best way to clean this carbon fouling without harming the metal? Is steel wool too harsh?


March 13, 2001, 19:10
I most generally use a copper penny as a scraper. They're far softer than steel and I haven't messed up a rifle that way yet. The carbon usually flakes or chips away nicely, though a good scrubbing with bore cleaner sometimes helps soften the buildup.

March 13, 2001, 19:50
3M Scotchbright pads and CLP. I use these on my AKs and FALs, and the gas pistons come out looking new. Wally World sells the Scotchbright pads. I would be leery using anything that might take off any metal. I am a firm believer that too much cleaning can cause premature wear. I also disagree with those that don't use any oil on their gas piston, after I started putting a light coat of Militec-1 oil on mine, I find clean up much easier. The only drawback I have found with oiling it, is the first shot ot two produces a very small wisp of smoke. I really don't consider this a drawback compaired to how much easier cleanup is...CC

March 13, 2001, 20:32
I also heard you can use a variation of this method by:

Putting part in a class jar with a Rubber pad under it and setting it on the Washing Machine to a few Cycles.

Homemade Ultrasonic Device!

Good luck!


ironman0311 - Ohio

March 14, 2001, 00:18
Scotchbrite pads DO take off metal. They are actually fairly abrasive. I prefer to use one of those donut shaped plastic dish scrubbers. It lets the chemical do the work without scratching anything and letting new deposit settle into the new scratches. The white pads aren't too bad, but as a rule I avoid all of 'em.

March 14, 2001, 01:56
Snakeshot: Very true. Since I've started useing a light coat of the Militec-1, all it needs is a wipe down with a CLP soaked rag. This thread is really starting to make me wonder if the Scotchbrite pads remove much metal. Think I will use them on a old gas piston, and measure the dia. of the piston face. After several healthy workovers with the Scotchbrite pads, I'll see if anything changes. Should be interesting to see what happens...CC

March 14, 2001, 03:44
CC, where do you get this Militec-1 oil? I've never heard of it.

March 14, 2001, 07:13
Why worry about how the piston and plug look on the inside. I just get them as calean as I possibally can, then put the thing back together. A little "staining" of carbon will not hurt the piston or plug. Are you going to have the gun inspected by sarge?

March 14, 2001, 09:08
I've had great success with Flitz Metal Polish and a stiff toothbrush. It leaves a nice finish on the metal that makes it easier to clean next time.

Rule .308
March 14, 2001, 09:15
What I have found to be a real time saver on grungy gas pistons is to put them in my drill press or the regular electric drill motor. Spin them up real quick, clean them and check for trueness really quick.

Rule .308

March 14, 2001, 09:24
Suggestion: If you use the drill press, put a couple of patches or something like that on there so that the chuck doesn't mar the end of the gas piston.

The Count
March 14, 2001, 09:58
I used some left over auto paint polishing compound from some auto body work/painting. Put a dab on my fingers and rubbed gently, took th stains right off. Washed piston in hot soapy water to remove any wax residue and wiped down w/hoppes9

March 14, 2001, 10:01
Scotchbrite will scratch GLASS! It most certainly removes metal, although not measureably with one cleaning. One dose of the pad might equal the wear of several thousand rounds, I'd reckon. Flitz removes metal also. I inadvertantly turned a satin stainless Ruger SP101 into a pimp gun using Flitz. Anything that polishes or shines removes metal. I used to have one of those rags for wipin lead and powder burns off of revolver cylinder faces. It also polishes metal, but is probably the milder than the pads or Flitz.

I let my piston head and plug soak in a bottle of Hoppes overnight to soften up the carbon. This removes most of the crud and chunks, but I don't bother to make it shine.


March 14, 2001, 10:48
I probably should clarify that the Scotchbrite pad will not remove an appreciable amount of material, but what it WILL do is cover the surface of the metal with minute scratches that make an excellent surface for future fouling deposits to grab onto- kinda like paint over park. The surface will be much easier to clean if it has a nice, smooth polish on it.

March 14, 2001, 13:19
So, how clean does the gas piston need to be?
I just hose mine off with brake cleaner & wipe with a rag. It cleans off the carbon build up but there are still surface stains.
Is it REALLY that big of a deal?
Unless a sparkling clean gas piston is critical to the operation of the FAL I'm not going to worry too much about it.

March 14, 2001, 13:40
I use 0000 steel wool and some oil like WD40 or Shooter's Choice, etc. I know this gets it cleaner than it needs to be.
Wear? I think it will take me quite some time to shorten the piston enough to affect function! http://www.fnfal.com/forums/wink.gif

March 14, 2001, 13:46

It isn't about the length, the issue is premature wear of the sides. Like Chupa said, so long as there aren't any chunks on the sides why bother?


March 14, 2001, 15:09
OK I just got through cleaning my FAL and I had st soo what I had here at the house would worke to clean the gas piston and plug. Ballistol will take the big stuff off. To get the plug nice and shiney, I used Brownell's JB Bore Bright. It made the chrome end of the plug look new. Did a fair job on the gas piston also. The Enterprise piston is rough but the JB got 99% of the carbon off.
Now as per my previous post. I probabaly will not do this every time. Normally I just get the big stuff off and not worry about the stains. I just wanted to see what would work.

March 14, 2001, 16:33
I also use the fine steel wool (0000) and a little Ed's Red* bore cleaner. Ed's Red is a homemade bore cleaner that contains acetone, kersosene, paint thinner, and Dexron ATF in equal amounts. The acetone is the primary carbon solvent.


* check the rec.guns site for the Ed's Red recipe and instructions.

March 14, 2001, 16:39
Gman: I got the oil from these guys www.usalubrications.com (http://www.usalubrications.com) . Chupacabra: I don't think it is really that big of a deal either. I know a guy that has run several thousands of rnds through his AK, and only wipes down the outside once in a blue moon. the funny thing about it is, this guy's AK runs great. A little carbon on the face of a Fal's gas piston might actually make it more efficient. More surface area for the gas to work with. I've heard DSA mills the face on their gas pistons a hair wider as to work better in most rifles. All I know, is wipeing mine down after shooting hasn't hurt it yet. The only time I make one shine is when I buy one that looks like it has never been cleaned. I like to see just whats under all that crud. You know, is there any pitting or what down there...CC

March 14, 2001, 17:53
A little Hoppe's #9 and a brass bore brush, a little scrubbing and IT'S CLEAN!


March 14, 2001, 18:05
Birchwood-Casey Lead remover cloth. Works like magic on carbon fouling, just a little rubbing and it is GONE! It is not abrasive at all, either. Also works great on stainless steel, I first tried it on my S&W 686 years ago and I was hooked. No other product compares. Available from Brownell's, and other sources.

"Visualize No Liberals"

[This message has been edited by Naz (edited March 14, 2001).]

March 14, 2001, 20:02
Here's a simple field expedient solution. It is so simple that I know you'll be pleasantly surprised. You'll probably even laugh, but it works.

I use a couple of paper match sticks.
(1)Wipe off the fouling from your piston
(2) Wet match head with water or saliva and use the wet match tip to WIPE off your fouling.

Just rub the wet match head on the build up and it will come off.
Requires about 3 match sticks and a couple of minutes.

Try it for yourself,


p.s. That's how we clean all our pistons here. HaHa!

NZ L1A1 Collector
March 14, 2001, 23:41
OK guys here's a bit of a run down on the Military aspect of cleaning the L1A1/FAL's


These are the words that were yelled at the platoon when I did my Basic training with the L1A1 by my platoon Sargent http://www.fnfal.com/forums/eek.gif

Your suppose to remove only the built up carbon on and around the gas plug & piston. Scorching is ok and is acceptable, so long as it’s not carbon built up. There is a special tool for cleaning the gas block called a ‘gas block cleaning tool’ this scrapes the carbon out from the inside of the gas block.

On the Canadian Combo Tool are a number of tools, a gas port cleaner (G), gas plug tool (J) and a gas block scraper (I). By far the best C-Tool for the Inch rifles. Most likely for the metrics too.

Bright and Shiny Gas plugs are a NO, NO and for inspection we use to acquire a spare set of ‘New’ looking Piston & Gas Plug for those special inspection occasions http://www.fnfal.com/forums/biggrin.gif

Canadian C1A2 Combo Tool & UK/Aust Gas Block Cleaning tool

Kevin Adams
Rifle, 7.62 mm, L1A1 Collector & Researcher.

March 15, 2001, 09:18
Hoppes and BRASS brush only. No abrasives. It doesn't have to shine, as long as it moves freely in the gas tube, it's good to go. I wouldn't worry about making it shine. You're just adding premature wear every time you "polish" it. I would suspect that most FAL owners (and a lot of other gun owners for that matter) wear their guns out more by cleaning than shooting. I'm pretty anal about caring for my guns too, but I'm not going to polish a part that's supposed to fit tight, because all polishing removes metal, and removing metal affects the fit. JMHO

[This message has been edited by Hambone_22345 (edited March 15, 2001).]

March 15, 2001, 09:45
OvenOff. Been using it on my AR bolts & carrier for years.

August 13, 2004, 17:44
been coating the head of the piston, and the chromed portion of the

gas plug with plastilube for several years now. learned this one from

bob landies at ohio ord. makes clean up a five minute job, as far

as the gas system goes. put me down for the hoppes, and bronze

brush to finish the job . also use a 3/4" wide radial brush, about 4

inches long, with a flexible handle, to reach the rest of the gas cylinder,

and also the chamber, and inside the combined device threads.

August 14, 2004, 10:56
Ballistol for cleaning and lube with nothing more than cotton patches. Wipe dry with clean dry rag & patches when finished. Scorching is minimal and actual carbon fouling is nada.

Combine with the DSA black piston and clean burning Aussie ammo and fouling is Zero. The piston only requires a quick wipe down with Ballistol and the inside of the gas block & tube gets a few wet/dry wipes with patches on a pistol cleaning rod.

August 14, 2004, 23:23

Look in the brownells catalog or head down to the local woodworking supply shop and pick up some Bronze wool.

Bronze wool is softer than even mild steel and blueing.

However it makes quick work of carbon deposits when combined with a penetrating oil like Kroil or Balistol, and even BreakFree.

Another use is for removing rust from blued firearms without harming the blueing.
Just add a couple drops of oil and scrub.

Carboned up gas tube?
No sweat, spin some of the Bronze wool into the bristles of a .45 cal Bore brush and go at it like a crackhead with a bad case of poison ivy.
Gets all the gunk loosened up so a couple of patches wipes out all the crap.

Shooting cast bullets in the pistol?
Bronze wool on the bore brush gets the crap out of the barrel AND does a great job on the carbon rings inside the chambers if you have been shooting .38's in the .357 or Spl's in the .44Mag.
Cylinder faces clean up quick without marring the blueing as well.

Just figured to share. I love the stuff and can't imagine life without it!

Best of luck!

September 28, 2004, 10:02
Scotchbrite for cleaning was mentioned earlier. I worked on this product a number of years ago. It is color coded to indicate the type and grit of the abrasive. Green or Purple contains 220 grid aluminum oxide, grey contains 400 grit siliconcarbide. White contains talc.

Obviously, all but the white can and do remove metal. The white was originally developed to clean Teflon frying pans. Since the plastic resin used for the binder is harder than the talc, it is safe to use on delicate things.

September 28, 2004, 22:29
Just clean with Hoppe's and wipe down. Any carbon build up on the sides will just add to the diameter and give you a better seal which equates to better force on the bolt carrier.

September 28, 2004, 23:36
What we used in the SADF was plain old white vinegar. Just tried it again recently and it works as good as anything.

October 01, 2004, 01:59
For routine cleaning CLP and an all purpose brush (green military toothbrush) works fine and leaves the teflon coating when the CLP carrier oil evaporates. This is adequate for "functional field cleaning". Every six months or so when I do a detailed cleaning, simple green and an all purpose brush or bronze bristle brush work great. This however removes the teflon buildup from repeated CLP usage so that process has to be started again. Many buddies of mine in the sand box are using militec-1 now. A light coat allowed to "dry" before exposure to the field is holding up well in the fine talc like sand over there. I personally do not allow ANY type of scouring pad or similar abrasives, plastic, copper, or otherwise anywhere near my weapons, isuue or personal, nor that of my men.

October 01, 2004, 04:38
CLP & old bronze brush, but don't make it sparkle because as Indy said it is a better seal. Just wipe what you can.:fal:

December 25, 2004, 02:29
I use Alumicut by Mystic Metal Mover, it's a cutting oil that works better than anything else I've tried. Non toxic and smells ok, and cheap!

September 15, 2006, 02:17
lead cloth,works wonders

September 18, 2006, 13:36
I used Hoppes or CLP and a brass brush. Light coat of RemOil afterwards. Just removing the carbon not all the staining.
They dont have to sparkle to work.

evan price
September 19, 2006, 04:10
Break open upper/lower, pull bolt carrier, top cover, gas plug & piston/spring. Douche liberally with nonchlorinated brake cleaner, down barrel, down gas tube, chamber/magwell area. Blow out with compressed air.
Set gas plug and piston/spring, bolt & bolt carrier on disposable shop rag. Douche with nonchlorinated brake cleaner and wipe really well with rag. Blow off with compressed air. Reassemble gas parts dry. Lube bolt carrier, bolt, receiver rails, chamber, barrel, etc. with TriFlow +PETFE industrial lubricant. Reassemble, cycle action a few dozen times. Run a wet patch through the barrel.

That's all it needs, about every few battlepacks or so.

Only thing to remember is the brake cleaner takes off every bit of oil so you need to wipe every surface of the rifle down with a semi-dry oily rag so rust doesn't start.

September 28, 2006, 00:15
An eraser.
Seriously. It works. Well, it works best if you tackle the job shortly after your shooting session.
And it is definitely not abrasive.

September 29, 2006, 23:15
Be careful of using anything abrasive on the piston heads, it can wear through the chrome plating. My first FAL built in 2004 now needs a new piston due to just that, I used #0000 steel wool primarily, with a purple scotchbrite pad on a couple of occasions, although to be fair, it may have had something to do with the age, and use on the rifle. South African serial # A0024, and RA6274 all #'s match. :)