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L1a1 Headspace Questions


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#1 PeacePipe

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Posted 20 July 2003 - 06:24 PM

I am building an L1A1 and I have already got the barrel on the receiver. The no go headspace gauge I have closes when I have the locking shoulder in it that came with the kit. I need to fin the right one. Tapco had locking shoulders but charges extra fo a specific size. I need a specific size, but I don't know which one. I saw on the web that there are a stepped bar that is used for FAL rifles headspacing. This tool costs like $60ea. With all the money I have in tools I don't want to spend more. I wanted to get the rifle profesionally blued, not parked and but an Ironwood Designs wood stock set. This helps on the US made parts and wood be really cool with a deep blue rifle and a light blonde stained wood stock set.
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#2 captain eddie Re: L1a1 Headspace Questions

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Posted 20 July 2003 - 07:54 PM

:fir: I've seen head spaceing kits which consist of different sized pins. If you have precise pins, or even drill bits, that might do it. Head spaceing is the most bothersome part of an FAL project. Good luck and keep us posted on the results. If possible, maybe when you complete the gun, you could post some pictures. -Captain Eddie
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#3 Thed Re: L1a1 Headspace Questions

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Posted 20 July 2003 - 10:06 PM

Warning: Headspacing a FAL and getting it wrong CAN MAIME OR KILL YOU.


There is 0.007" of headspace max tolerance to work with. I would ONLY use machinists "Sizing Rods" for selecting what size of replacement locking shoulder you need. Use nothing else. I would suggest the FAL Files to verify the information I have said. When working on firearms, trusting or following information you find can end your life.

In FN-FAL armorers kits they have that "stepped sizing rod". I have seen two versions of it, one being a set of (two) five position rods, the other being a sizing rod with ten slots. On certain Metric FN-FALs there is a number printed on the side of the locking shoulder, this number corresponds with the specific position on the sizing rod. This makes it real easy to do Headspace.

Assuming you can find a vendor who sells the numbered locking shoulders and you have the FN tool. This can be a hard thing to do.

I used Machinists Sizing rods and brought a Micrometer to a gunshow in DFW. I stood in front of a "Vat-O-Shoulders" and measured until I found one that was nearly perfect, erring to 0.001" under.

Warning: Check the side of your reciever. The Locking Shoulder has a "head" on it. Some are shaped like an oval with flat sides, some are shaped like a figure eight. Make sure the head of the locking shoulder matches your reciever profile before you purchase it.

The information I have listed is for Metric FAL rifles. There may be details found only in L1a1 or "Inch" style FALs that I am unaware of.

If you continue to have trouble finding the tools needed, I have them I can mail them to you. However I would require a $100 deposit which I would refund to you after I got them back. You also may want to check eBay for some FAL tools, you may get lucky. Email me if you need the sizing rod set and a Micrometer.

A Fellow FAL Owner,
-Thed ok>
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#4 PeacePipe Re: L1a1 Headspace Questions

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Posted 21 July 2003 - 08:28 AM

Thanks. I know what you mean about taking gunsmithing advice on the web. I will not trust my life to drill bit headspace. You offering to send me the tools to me is mighty fine of you. I would want a deposit too. I have a PayPal account, do you? I will send a email. I live in the middle of nowhere and the nearest gunshow is a four hour drive. I looked at that FAL files place and it looks good.
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#5 captain eddie Re: L1a1 Headspace Questions

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Posted 21 July 2003 - 11:43 AM

:fir: If the headspace was too tight, is it possible that the gun when fired, would not eject? I've been having some difficulty with my FAL and was wondering about this. I would appreciate any input. -Captain Eddie
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#6 Thed Re: L1a1 Headspace Questions

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Posted 21 July 2003 - 08:31 PM

If the bolt was able to fully close on the round the only risk you have is excessive headspace, not too tight (unless you are using commercial .308Win and not the 7.62x51mmNATO in which it was made and designed for, there is a difference).

What ammo are you using and what position is the gas selector on?

The SKS carbine and FAL are similar that the bolt lockup has to be freed by force on the carrier. Is the spent cartridge able to be extracted by opening the bolt manually? Is it much more difficult than opening the bolt manually?

Didn't you say on another thread that you built your FAL from a parts kit? Who is the receiver maker and what parts kit are on it? This would help.

-Thed
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#7 captain eddie Re: L1a1 Headspace Questions

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Posted 21 July 2003 - 08:58 PM

:fir: I have tried Portugese, Indian, and Remington ammo. The Remington is only one that even came close to working. The gas adjuster is on 1. The gas regulator is on A. The spent cartridge can be extracted manually. The bolt doesn't seem to be any harder to open with a spent case in the chamber as it does with an empty chamber. I used a G-1 parts kit from DSA and a receiver from Imbel. -Captain Eddie
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#8 Thed Re: L1a1 Headspace Questions

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Posted 21 July 2003 - 11:07 PM

New batch of Indian or the tarnished Indian Milsurp that has been floating around for that past few years?

The Remington. Commercial .308?

When using Military Surplus 7.62x51mm Ammo, Namely and Specifically the Portugese with the NATO Cross Headstamp, did the action fully close on every round or were there cartridges that did not have full bolt close?

What US Compliant parts are installed?

My first guess it that it has nothing to do with headspace, but the gas system. If the gas adjuster is set to forcing all available pressure to the piston and it is still not moving then there is a major leak or block in the system. If the Remington Ammo is commercial with chamber pressures 20%+ higher than that of 7.62NATO it would be enough to over ride this possible leak or block. I am wondering if any of the US Compliant parts are US made mixed with the German. If there is friction on a US made gas piston or Gas tube that could override the system from correctly cycling.

I had a PreBan C1a1 (Canadian L1a1) that had the Gas Adjuster position spring connected to the Gas tube. The same Spring/pin part held both in place. When Dialing the gas system in, the spring collapsed and the Gas tube was rattling around. The bolt carrier would kick back about 1/2" where you could see the bolt when fired. Thats it. If there is an American tube in German selector parts and block is there a gas leak?

Speculation at this time. I need more information.

-Thed
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#9 captain eddie Re: L1a1 Headspace Questions

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Posted 22 July 2003 - 02:16 PM

:fir: The Indian ammunition appears to be relatively new. The head stamp on it is 7.62 M80 86. The bolt seems to close okay with the Portugese; however, with the Portugese ammunition, after it is fired the bolt carrier is always about a half inch back. Apparently it opens a ways, but then doesn't fully rechamber the empty case. The US parts are the furniture, and trigger, sear, and hammer. There is no muzzle devise. The gas tube was very loose initially, but I sanded the end of it just enough that I could turn it another half turn, making it now very tight, as far as I can tell, anyway. In the past, I tried a US gastube from TAPCO, but it was a little loose and didn't seem to help. I also have an Imbel parts kit. I tried the gastube, gas piston, gas regulator, and gas adjustment ring from the Imbel, but to no avail. When I first assembled the gun, the empties were extremely difficult to extract manually. The bolt seemed to be a little bit tight in forward part of the receiver ( the part just behind the barrel that controls up and down and side to side movement of the bolt). I did a little sanding around some of the tight places, and now the empties can be extracted manually very easily. I haven't tried the Imbel's gas piston or other gas system parts since making that modification. I had tried another G-1 bolt and bolt carrier, both before and after working on the gun, but to no avail. The gas adjustment ring on the gas block seems a little bit loose, but I don't know if that could be the problem now or not. Do you think that could do it? The Remington ammo was just regular commercial ammo. Soft point hunting loads of some sort. The first time I tried them, the gun without a magazine actually ejected the case, but once I installed the mag, that was the end of it. I have about five different clips, and none seem to work any better than the other. I have pretty much run out of ideas, so any input is greatly appreciated. -Captain Eddie
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#10 Thed Re: L1a1 Headspace Questions

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Posted 22 July 2003 - 05:24 PM

Sounds like a gas leak is the root of the cycling issue.

Was the rifle headspaced, and by who?

Specifically what parts were sanded?

-Thed
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#11 captain eddie Re: L1a1 Headspace Questions

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Posted 23 July 2003 - 11:21 AM

:fir: The rifle was headspaced by me, with some help. We removed the extracter and put one layer of masking tape on it to see if would close, and then added another to see if it would close. After two peices of masking tape were put on the cartridge, the bolt would not close. I did the same thing with an SKS for comparison. I believe the headspace is about 7 thousandths, but I'm not 100% certain, it could be less. Probably not the best way to do it, but I didn't have the right tools, or the money for the right tools. I sanded the receiver rails, and forward portion of the top of the bolt. Also a little bit of the outside of the extracter, as it seemed to be rubbing quite hard on the bolt carrier. -Captain Eddie
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#12 Thed Re: L1a1 Headspace Questions

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Posted 23 July 2003 - 07:27 PM

If you used a 7.62NATO cartridge there is a wide range of sizes the cartridge is. This is one of the fundamental differences between 7.62x51mmNATO and .308winchester.

7.62x51mm NATO is manufactured to a standard that can be achieved by all NATO countries, thus all of this ammo should have the "NATO Cross" headstamp. This is why I asked you specifically about the Portugese ammo. It is made to a specific standard. The Chamber pressures of this round are somewhere around 50,000PSI. These shells have a 0.005" tolerance between cartridges. This means that not every cartridge is not the same size, and there is a acceptable ammount of "slop" permitted.

The Commercial .308 Winchester is different. It is governed by SAAMI tolerances, and it is manufactured to far tighter tolerances than 7.62NATO. The .308win cartridge is typically the smallest allowable variant size in 7.62NATO. The Chamber pressures are often 60,000PSI+++

This means that the FAL rifle, designed for this lower pressured cartridge, is not made for the .308WIN. If using .308win not only is it more pressure that it is designed for in regular use (which under ideal conditions it can take), but EVERY .308win is contibuting to Excessive headspace because of its tighter manufacturing tolerance.

You rifle was not headspaced properly. You need to find, borrow, buy, or rent some 7.62x51mm Headspace gauges. There is no other safe alternative. You do not know that your rifle is set properly. If you used the original locking shoulder and sanded anywhere on the bolt to fit, I would be terrified to fire it.

The masking tape idea works fine for solid bolt action rifles which have some forgiveness with headspace. Not the FAL. The bolt carrier drops the bolt behind the cartridge when it is loaded in the chamber. The geometry is critical, because it holds the bolt in place during firing and is not loosened until the Gas System and the piston kicks the carrier back, thus pulling the bolt out of the chamber blocking position. The action is similar to the SKS.

If the geometry and spacing tolerances are not right, the bolt will not be locked in place during firing and you can get a bolt carrier, bolt, cover and some rear sight pieces forcably introduced to yuor inner cranium. Sanding can and often will screw these all up. And this is with 7.62x51mmNATO.

Let alone with often 120%+ higher pressure of Commercial .308win. You rifle cycled with a Gas leak most likely because of the higher pressures I mentioned.

I am saying this so you do not get killed or injured. Not to be an ass.

The first step is to make sure your rifle has the proper headspace. Did you sand the rear of the bolt, the reciever other than the rails, or the locking shoulder. If you did the parts may be unsafe and unfixable with the level of tools you own.

Do you have an untouched bolt? If you do than there is a chance all is not lost. I am interpreting that your bolt had too tight of headspace tolerance, and by sanding the front you got it to fit. You are not supposed to use force when headspacing so its possible that you are way too tight. What I am worried is that the geometry (location and conditon of the angles and planes on the critical parts) may be sanded uneven, thus rendering it highly dangerous.

With the right sized locking shoulder, a bolt should drop in fine with no wiggle or sanding. Rounding corners is BAD.

Do you have left over parts. Sell them on Ebay, and use the money to buy headspace gauges. If you are serious about gunsmithing it is a MUST. What do you have left in parts?

You should be able to find a Go, No-Go, and Field gauges for under $60 delivered. I will look to see if there are any deals out there.

-Thed
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#13 captain eddie Re: L1a1 Headspace Questions

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Posted 23 July 2003 - 08:22 PM

Did you sand the rear of the bolt, the reciever other than the rails, or the locking shoulder.


No, I did not sand the rear of the bolt. I never touched the locking shoulder either. I only touched the rails. They were not machined as smooth as they should have been, so I simply polished them. At the very front of the bolt carrier, the part of the bolt that contacts it, and the outside of the extracter that has the hole in it for take down, that is all that I ever sanded. I know that it was not headspaced properly, but none of the cases seem distorted. Probably close to a hundred rounds have been through it. Only about maybe 6rds of Remington have been put through it. The Portugese ammo does have the NATO cross on it. I tried swapping a different gastube, gaspiston, and gas regulater but to no avail. Any idea where the leak might be? I know without seeing it would difficult to guess, but any theories could be helpful.-Captain Eddie

P.S. I am planning on having it proffessionally headspaced.
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#14 Thed Re: L1a1 Headspace Questions

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Posted 23 July 2003 - 09:04 PM

If you are going to get the rifle professionally headspaced, Make sure he has 7.62x51mm gauges. If he says that .308winchester will work fine than pack yer rifle and leave (unless he is goin to do if for free. Then its nice to know if the minimum tolerances are met and can give you an estimate of you headspace.)

Chances are the gunsmith wont be able to fix it if the headspace is off. He will then have to order parts and upcharge you while you wait.

the .308win VS 7.62x51mm is a great indicator on a persons experience for rifles. Remeber that. People who say they are interchangeable and say they are the same thing have never headspaced a FAL. There are all sorts of little distinct things like this in firearms that can tell you alot about ones experience.

I personally would buy your own gauges and do it yourself. If you are serious about building your own rifles, than it is a must. It will also alow you to check your rifles over time. It does not cost that much.

I would not fire your rifle until this issue is fixed. All other problems are less important.

Strip the rifle gas system down.

I noticed in one of your posts you gave a guy SKS advice and said something about not using grease. I use light weight grease.

Go to Wally World and buy yourself a can of aerosol "White Grease" for $1.77 abd a can of carburator cleaner for $0.78. Carburator cleaner is my favorite bore solvent as well. I usually buy 3-5 cans at a time. I use an old 5 gallon bucket and tip the rifle down and spray down the bore.

Its summer time, so clean and coat the gas piston in the white grease and let it heat up out in the sun all day (Im in Texas so its easy). I actually give all the rifles this treatment. I coat all the surfaces of the metal and let this white grease soak in. Here in Texas its hot and humid. This treatment will help eliminate pinprick rust in your blueing and park, and will act as a tougher protective layer better than oil.

After geting hot and baking in for hours wipe off all excess.

On moving internal surfaces, it helps alot on reducing friction.

Keep it away from the bore, crown, and chamber!!!

Get a paper clip and scrape out the gas block. Confirm that there is no cosmo/preservative or carbon build up restricting flow. The carburator cleaner will help in this. use the red hose that comes with the can and spray a steady stream down the gas block into the barrel. If it does not flow out the barrel than you have blockage. Likewise clean the gas plug (A/G) knob.

At the range, I like to use carburator cleaner to swab out my bore on patches because it totally evaporates. I have noticed a reduction inflyer shots (first shot out of barrel taking out miniscule excess oil and residue).

The spring on the gas piston, gas tube should all be able to slide with finger pressure. if there is some friction make sure the gas tube is free of burrs and snag points. If your model of gas tube has holes drilled into it where it mounts to the gas block, this will be the greatest area of burrs or distortion that could cause a problem. After this is all reamed and cleaned, with a baked on layer of white grease it should slide fairly easily. I personally leave my piston with a layer of grease on it. After 200 rounds, I pop it out, and the white grease is black. I wipe it off with a rage, give it anf the spring a quick spray with a spray solvent (carb or wd) and coat it with a new layer and but it back. If you are good/excellent about cleaning your rifle I would suggest this.

On the G-1 it has a closed ear gas block? Is the barrel a G-1 Barrel? you said that you had an Imbel kit. Give me a breakdown of what parts you have. I want to rule out Inch Vs Metric conflicts of your parts. I have used the made in USA Tapco parts and I have mixed feelings on them.

This may be an obvious problem. Timing on the gas adjuster dial. Is it installed in a fashion where it is fully closed on the port at the one position?

I have typed enough on this topic for tonight.

If you could, post separate subjects into different paragraphs. As I repsond to what you say, it makes it easier to keep on track to what your are asking. One big paragraph makes it harder

-Thed ok>

Edited by Thed, 23 July 2003 - 09:07 PM.

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#15 captain eddie Re: L1a1 Headspace Questions

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Posted 23 July 2003 - 10:08 PM

The kit was from DSA. It was refinished.

The barrel is a G-1, it's the one that came with the kit. It is a closed ear gas block.

All parts are currently the original parts that came with the kit, exept for the furniture and sear, hammer, and trigger.

The receiver is currently the only Imbel part. I have had other Imbel parts on it in the past (gastube, gas regulator, gas adjustment ring, and gas piston), but have removed them.

I had a TAPCO gas tube on it for awhile, but it fit a little loose, so I did some work to mine, and reinstalled it. The gas tube seems to be fairly tight now. The gas adjustment ring spring is not as strong as the one on my Imbel, does that matter?

I ran a thin wire down through the gas port, so I don't think it is plugged.

The gas piston and spring move through the gas tube fairly easily, so I don't think it is snagging.

The gas adjuster seems to be lining up where it is supposed to. It is as tight against the gas block as it can be turned. It will turn slightly past the vent hole, but I keep it set so that it covers the hole.

Tommorow, I will check the gas block for any crude that shouldn't be there, just in case. By the way, I think some of that Indian ammunition may be slightly corrosive, as the threaded part of the gas tube is now rusty. Nothing serious, just a little brown. -Captain Eddie

Edited by captain eddie, 23 July 2003 - 10:09 PM.

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