.308 WIN Century Arms R1A1

[Haans]

So I bought an R1A1 from a coworker last fall. He had never fired it before, and had bought it from an old friend.

Anyway, I took it to the range at Wilbur Wright FWA for the first time late last year or early this year, and I found that after every shot, the magazine would get jarred loose and would fail to feed the next round. So I took it to Ludco Gunshop over in Parker City and had him send it to a gunsmith. I got it back, and was told that it was a problem with the magazines not being properly fitted to the rifle. (I have 5 magazines for it, though I only sent 3 with it, so only 3 are fixed )

Anyway, I got back to the range with it just today, and while the three magazines worked properly, I did note that after the first 20 shots, I started having failures to follow again, though this time it was that the bolt wouldn't follow through all the way. My -guess- is that I need to fiddle with the gas nozzle (I forget the proper word).

Does anyone know an easy way to gauge how much gas pressure I need to be setting this rifle to fire with? Possibly a way that doesn't involve shooting it? (Long shot, I know, but I rarely go to WW FWA and there are no public rifle ranges closer.)

 

[paddling_man]

I've got an FAL manual I'll send you. PM your email addy to me.

 

[sporter]

Magazines not properly fitted to rifle? Sounds like something is way out of spec on your rifle.
Is it a Century receiver?

 

[Haans]

As far as I know, it is a Century Arms receiver, yes. And paddling_man, I appreciate the offer but I actually have a Century Arms manual for it that I found on the internet. Would the proper FN FAL manual say anything different or say something more clearly?

 

[HandK]

Do you have a picture of the gun? If I saw a picture I might have the manual for it I have PDF manuals for just about every military gun out there and would be glad to email you with it, Let me know if I can help. Gary

 

[paddling_man]

As far as I know, it is a Century Arms receiver, yes. And paddling_man, I appreciate the offer but I actually have a Century Arms manual for it that I found on the internet. Would the proper FN FAL manual say anything different or say something more clearly?

YES.

I'll look but I believe the FAL manual is a real armorer's manual.

I've seen the Century pamphlet they call a manual. I believe it says something like, "adjust the gas knob for best performance." The whole "manual" is three pages long??

I have an L1A1, not an R1A1.

This poster describes it well:

1) with rifle unloaded and on safe ( of course ! ) set gas to zero
2) load 1 round in magazine, insert mag and chamber round ( never ever feed by hand into the chamber as this does not allow the rifle to properly cycle )
3) fire .... there should be considerable recoil and the empty should fly out in the blue yonder about 5 meters to your right
4) now set gas to one ( 1 ) and repeat above. do this 3 or 4 more times. the empty cases should land closer as the gas port is opened further until at one point the rifle will not cycle anymore.
5) set gas one before the number at which it stops cycling ( i.e. if it stops on 6 set on 5 ). my L1A1 will work down to a "7" gas setting. Yours might differ.

Ammunition has a lot to do with the gas setting as well. The stuff at Walmart is too expensive and not suitable for use in military rifles. Save it for a bolt gun or a Walmart rifle. The best 7.62x51 out there are Australian and South African. The Argentine and Portuguese( FNM )ammo is okay albeit a bit innacurate. Stay away from the Indian ammo that Cheaperthandirt and places sell, it is dangerous garbage.

The manual from FN has three pages devoted to the best method for determining the appropriate gas setting.

o) Method of gas setting
There are several different ways of finding the
correct adjustment but we suggest the following
method, which has, we think, proved itself the
best :-
- Insert an empty magazine in the rifle;
- All firing is carried out by inserting the car-
tridges by hand, one by one into the empty
magazine, through the ejection opening.
- The correct setting is determined by the
point at which the holding open device
engages the mechanism and holds it to the
rear, or fails to do this.
b) Operations
Operation 1. After
right down against
screwing the gas regulator
the gas block (fig. 8), un-
screw by one complete turn so that the figure 7
is in line with the axis of the gas escape hole
(fig. 9). This is the fully open position and,
when a round is fired, causes a “short recoil”,
identifiable by the holding open device failing
to engage the mechanism.
Operation 2. Close the gas regulator click by
click and fire a cartridge after each adjustment
until the breech block is held to the rear by the
holding open device.
Operation 3. Now verify by firing several car-
tridges, one after the other, in the way described
above.
Operation 4. If any shot results in a failure of
the holding open device to engage the mechanism, repeat Operation 3, after closing the gas
regulator by one click.
Operation 5. If necessary, repeat Operation 4
until 5 consecutive shots result in the holding
open device holding the mechanism to the rear
5 times.
Operation 6. The gas setting for the rifle is now
determined, but it is always advisable to allow
a small reserve of “working” gas by reducing
the gas escape by two additional clicks.
Note
-If the special spanner (fig. 10) is not available,
adjustment can be made with the point of a
cartridge (fig. 1 I), or even by hand.
-
-
Fig. IO Fig. 1 1
Before leaving the factory, every rifle has been
adjusted for correct gas setting.
In principle, the soldier should not alter the
gas setting; this operation ought to be done
in the presence of the unit armourer, or an
instructor.

In practice, the force with which the spent cor-
tridge case is ejected gives on invaluable indication of the gas setting. An ejection of cases
to a distance of 1.50-2 m from the rifle and
at f 45” in relation to the barrel axis can be
considered normal. Violent ejection shows
that too much gas is being admitted and, in
this event, the gas escape must be increased.
On the contrary, weak ejection shows that
insufficient gas is being taken in and, in this
case, the gas escape should be reduced.

From the FAL & L1A1 Home Gunsmithing guide, Lesson 205:

LESSON 205: TUNING THE GAS SYSTEM
(Revised 09-22-00)
There are several factors that contribute to proper cycling in a FAL. Most important is the gas
pressure created from the burning propellant that forces the projectile down the barrel. As the
projectile passes the gas port, the pressure works in three directions. First, it continues to propel the
projectile down the barrel; second, it is exerted outwardly from the inside of the cartridge case
against the chamber walls. Third, it travels through the gas port, through the gas block/sight
assembly, and puts pressure on the face of the gas piston, driving it back against the bolt carrier and
initiating unlocking and cycling. The timing of this step coincides with a drop in the pressure exerted
inside the cartridge case against the chamber walls, which allows the cartridge case to extract. When
the projectile exits the barrel, pressure drops to zero because the gas vents through the end of the
barrel. There is a pressure-time curve; critical to cycling the action is not just the total volume of gas
and gas pressure, but how long that pressure is maintained. The longer the barrel, the longer the
projectile blocks gas from escaping out the end of the barrel and directs it through the gas port. A
shorter barrels mean a shorter time that the projectile is between the gas port and the end of the
barrel, and must have a larger diameter hole to bleed the same volume of gas in a shorter time frame.
If the hole is too large, the outward pressure exerted by cartridge case has not dropped sufficiently
for the case to be extracted, but the piston is forcing the bolt carrier to the rear anyway resulting in
extractor failure or the extractor rips the rim off the cartridge.
Another factor is muzzle devices. L1A1 style flash hiders are designed to dissipate and cool gas in as
large an area as possible, thereby reducing the flash signature. Muzzle brakes that have an exit hole
of a smaller diameter than the inside of the device, trap gas in this expansion chamber. As the larger
volume of lower pressure gas strikes the portion of the muzzle device where the exit hole is reduced,
it creates back pressure, which adds to the pressure on the gas piston. This is why removing a
muzzle brake from a gun that was tuned with one in place may prevent it from cycling.
A gas plug fits into the front sight assembly and both retains the piston and directs gas flow. There
are many styles and not all are compatible with all front sight variations. Israeli are shorter than
metric and use a longer gas piston. Inch pattern
are also shorter than metric, but use a gas piston
that is slightly different, but interchangeable with
metric. There is a hole in this piston that directs
gas to the piston. Rotating this piston 180
degrees blocks the gas from hitting the piston.
This position was used for imparting maximum
pressure on rifle grenades, but has caused many a
novice panic at one time or another over their
"single-shot" rifle. A line, a scallop cut, an "A"
or a Hebrew aleph (א) usually indicates the firing
position. The single shot grenade position is either unmarked or marked with a "G" or a "Gr." As the
gas passes through the plug and hits the piston, the piston begins moving rearward. At this point, the
gas pressure may vent through a hole at the rear of the front sight assembly. A rotating ring called a
gas regulator covers this hole. The gas regulator is numbered, depending on variation, from 1 up to 7
on metric, from 1-11 on inch (sometimes not numbered at all, such as Brazilian guns). At 1, the hole
is completely covered, imparting maximum pressure on the piston. At the high end, the hole is
uncovered, allowing gas to bleed off and reducing pressure on the piston. The pressure may reduced
so much as to prevents cycling.
Different ammunition has different pressure curves, so you must experiment with each type of ammo
you use. The higher the number (the more gas bleeding off), the less violent the recoil and the less powerful the ejection of the spent case. On weapons with a last-round bolt hold-open, open the gas
port all the way, then fire with one round in the magazine. Close the port one number at a time until
the bolt locks open consistently 5 times. This is your maximum gas setting. For reliability, drop one
or two numbers (2 to four clicks) more. If you have an L1A1 style gun, or one that lacks the last-
round bolt hold-open device, you will have to experiment to determine the ideal setting. If it only
works on 1 or two, there is not much room for error, such as when your gas port begins to foul. The
remedy is to increase the diameter of the gas port.
Access the gas port by disassembling your front sight assembly, removing the gas regulator, plug and
piston. On metric guns, remove the front sight. On inch pattern guns, the gas port is drilled
diagonally from behind the front sight into the barrel. On metric guns, the hole is vertical through a
hole behind the hole through which the front sight is threaded. Both guns with standard length
barrels have a nominal gas port diameter of .096 - .098î.. A conservative gunplumber will increase
the diameter a bit at a time, until the desired pressure is achieved. With an 18" barrel, I am usually
successful with a .116" to .118" . 16" barrels usually work with a .118, occasionally with a .120. At
one time, inch pattern rifles with 21î barrels were ìproduct improvedî to a 2.75mm (.108î) I
recommend, however, that you make the hole no larger than necessary for the desired results. Too
large a gas port can "shave" bits of copper off the projectile, causing fouling and malfunctions, or rip
cartridge rims due to the chamber pressure being too high at the moment of attempted extraction.
The following table identifies relevant drill sizes.
#41 .0960"
#40 .0980"
#39 .0995"
#38 .1015"
#37 .1040"
#36 .1065"
#35 .1100"
#34 .1110
#33 .1130
2.9mm.1142"
#32 .1160"
3mm .1181"
#31 .1200"
3.1 mm.1220"
1/8" .1250"
If a full length barrel with a .096"+ gas port is not cycling, it is probable that the gas piston is too small in
diameter or the tube is too large. There should be no lateral movement of the piston in the tube. This allows
gas to blow by the piston, instead of actuating it. The easiest remedy is to buy a new piston. Failing that,
you can build up the tube or piston with nickel plating or hard chrome until they are a tighter fit. Insure also
that the gas tube is indexed properly and the retaining roll pin installed correctly. There are two holes
pointing downward oblique to the gas tube. As the piston reaches its maximum travel, it clears these two
holes, allowing any excess pressure to bleed off and reduce wear on the gun.

 

[POTI]

you need inch mags i bet... not metric

 

[m39fan]

"you need inch mags i bet... not metric"

It is likely a Inch receiver. However, with that said, NORMALLY Inch guns work with Metric OR Inch magazines. I had the same problem with one several years ago and IIRC it was the spring for the mag release. It might be worth your while to pull the release check for any burrs or irregular angles on the face of the latch, clean thoroughly and reinstall with a new spring. I believe Gun Parts Guy has some.

As to the gas system, I'd take it part and clean thoroughly. Check the piston and valve for damage & reassemble. Please note that on two of the R1A1's I've owned I've had to replace the gas piston with new ones to get the system to function properly. The Tapco made unit worked well for me and ads another US made part to your count! When putting everything back together, make sure the gas plug is back in correctly.

Unfortunately, due to differences in ammo, there's not a "good way" to dial in the rifle without firing the ammo you're going to use. When you get time to head to a range, dial the gas regulator down to the bottom and fire a few rounds. Keep adding restriction until you're happy with the functioning and aren't throwing cases farther than your projectiles! Then sit back and enjoy!

HTH,
Mike

 

[gska3873]

You say that it is having a "failure to follow". Do you mean failure to extract or failure to feed? If it is failure to extract it could be in the gas system with not enough gas due to setting or gas leak or the gas piston could be binding from an over/under timed barrel (very possible if built by Century). If it is failure to feed and a Century reciever it could have the magazine notch cut slighlty low in the receiver with the lower portion needing a little weld to raise it up or the bottom of the bolt could also be rounded off instead of having a "square" edge causing the bolt to ride over the next round.

 

[2cool9031]

Am I missing something here...aren't you guys talking about a L1A1 not a R1A1.....I have a L1A1

 

[m39fan]

2Cool - Century labeled theirs as R1A1's. All of them that I've seen are L1A1's with new Century receivers but I've heard they did make some with Metric parts as well. So, when you see R1A1 in posts you can usually figure it's a Century Frankenfal rather than a South African produced weapon (the original R1A1) or a typo.

Hope this helps,
Mike

 

[gska3873]

Hello, The South African made FAL liscensed by FN and built by ARMCOR is the R1 not the R1A1. R1A1 is just a designation that Century made up for some of their rifles. Thanks.

 

[Haans]

You say that it is having a "failure to follow". Do you mean failure to extract or failure to feed? If it is failure to extract it could be in the gas system with not enough gas due to setting or gas leak or the gas piston could be binding from an over/under timed barrel (very possible if built by Century). If it is failure to feed and a Century reciever it could have the magazine notch cut slighlty low in the receiver with the lower portion needing a little weld to raise it up or the bottom of the bolt could also be rounded off instead of having a "square" edge causing the bolt to ride over the next round.

Sorry, meant failure to feed. The bolt carrier will extract the spent cartridge, but doesn't seem to have enough force to chamber the next round and then go into battery. Could it possibly be a spring issue?

 

[gska3873]

Here is some good info on FTF/FTE and what not for FAL newb's from the FALfiles.

Among the most common symptoms of FTF/FTE (failure to feed, failure to extract) are the following:

1. Bolt riding over the cartridge either causing a jam or missing the cartridge altogether

2. New cartridge only partially chambers, spent casing extracts and may or may not eject

3. New cartridge jamming against back of receiver

4. No apparent movement of bolt or carrier regardless of gas setting

5. Partial extraction of spent casing regardless of gas setting, casing jams hard in chamber

6. Gas tube blows out of gas block

7. I've done all the stuff to get more gas but my FAL STILL won't cycle properly.

8. Bolt closes easily on headspace guage but will not chamber round. Jams up tight.

FIRST, have you checked and made sure that your extractor hasn't broken?

I will deal with them in order.

Before you do anything, ensure that the rifle is assembled correctly and there are no broken parts.

1. Bolt riding over the cartridge – This is a FTF problem and can almost always be traced to three common problems.

a. First, check to see if the magazine is being held in the mag well tightly. If it is loose, your problem is most likely a mag catch that is too short. The solution is to replace it with one with an extended mag catch. Tapco offers extended mag catches for about $10. Alternately you could weld a small bead on the end. In either case you will have to “file to fit” for a good tight hold.

b. Second, take the bolt and carrier out and remove the dust cover and close the rifle. Insert a mag with at least two cartridges into the mag well. Now look at the mag from the top of the receiver to see if the mag looks like it is symmetrically positioned in the well, especially near the front. Most often it is well used mags that have this problem which will manifest itself as a FTF from one side of the mag or the other. Also, check the mag for a weak spring. In either case. Get a new mag and throw this one away. (Yes, you can replace a weak spring if you have another bad mag laying around but at $10 each for new mags, it is hardly worth it.)

c. Third, look for long fairly deep scratches in the cases of cartridges that have jammed. This is usually caused by sharp edges on the feed plate at the top of the mag well and more often on cartridges that feed from the left than the right. Polish the edges of the feed plate with 400 grit wet or dry or finer.

2. New cartridge only partially chambers, spent casing extracts and may or may not eject

a. If the spent casing eject reliably, check to see if the bolt carrier moves easily in the rails. Imbel GL (gear logo) receivers are well made but a common problem is that the receiver rail is directly beneath some of the lettering stampings and occasionally gets distorted from an over zealous machine operator. Gunplumber suggests taking a small bastard file and gently but firmly filing the “hump” off.

b. If you have an aftermarket HTS (hammer, trigger, sear) combo installed, remove and replace them with the pieces that were provided with the kit for troubleshooting. Century is not known for tight adherence to tolerances and their HTS will often cause FTF problems because they drag on the bottom of the bolt or carrier.

c. Make sure that the recoil tube is straight and undamaged and that the spring and recoil plunger are lightly greased. A small amount of grease will not cause the rifle to lock up.

d. Check for weak recoil spring. R&R as necessary.

e. Perform gas checks in Number 4. c, d, e, f, and i.

3. New cartridge jamming against back of receiver

a. This is most common with Century receivers. I have bad news, there is a problem with the design of the feed ramps that cannot be fixed easily. Polish the feed ramps with a felt tip and rouge on a Dremel and it may fix it. Others have suggested MIG welding or brazing a small ramp and Dremeling it to shape. Proceed at your own discretion.

b. This can also be a problem caused by a slightly out of spec barrel. The barrel around the chamber cut should have a bevel about 1/8" wide. You can widen it slightly with a small file and polish it with fine sandpaper and then a felt tip and rouge on a dremel.

4. No apparent movement of bolt or carrier regardless of gas setting

a. Check that the gas plug is in the “A” position.

b. You DID remember to put the gas piston back in, didn’t you?

c. Check to make sure the gas tube is pinned in place and has not rotated. Ideally, the exhaust ports in the gas tube should be at 8 o’clock and 4 o’clock but if they are at 10 and 2, it will not affect operation.

d. Ensure that the gas port is not obstructed.

e. Check that gas piston is not undersized or worn. Proper diameter is between 0.429” and 0.431”.

f. Excess leakage around gas tube, see No. 6

g. Check that the bolt carrier “rat tail” is straight and in the recoil plunger detent and not jammed against the back of the lower receiver when closed.

h. Take the gas piston spring out and roll the piston on a flat surface to check for straightness. Reinstall the gas piston with the bolt and carrier removed. The piston should fall freely through the gas cylinder and gas nut. If not check gas tube and gas nut for roundness and damage.

i. Check for cracked gas block.

j. Make sure you haven't put a metric gas plug in an inch gas block. A metric gas plug is about 3/16" longer than the inch plug. The gas plugs are not interchangeable.

5. Partial extraction of spent casing regardless of gas setting, casing jams hard in chamber

a. This is most often a problem of not enough gas. What is REALLY happening is that the spent casing is going back a small distance and then being pushed back forward into the chamber and shares solutions with No. 4. c, d, e, and f above.

b. Check that the gas piston moves freely. See 4. h above.

c. Check that carrier moves freely. See 2. a, b, and c above.

6. Gas tube blows out of gas block. This is a common problem in the G1 kits and the solution is both simple and cheap.

a. First, clean the thread of the gas block and gas cylinder and spread a small amout of solder flux on the threads.

b. Install and pin the gas tube with the exhaust ports at 4 and 8 o’clock on the rifle as if you are preparing to shoot it without the gas piston or spring installed.

c. Using Mapp gas, heat the threaded area and apply silver solder (preferably high temp silver solder because it is stronger) until it flows into the joint.

d. After the area cools, clean the excess flux off the area (some flux is acid based) and you may file the high spots off the solder with a small file if your solder job isn’t too pretty or interferes with the gas regulator.

e. With a Dremel cut off wheel, cut the gas tube off about 2 inches from the back of the tube (the end closest to the receiver) and discard it. Use sandpaper to smooth the end off.

7. I've done all the stuff to get more gas but my FAL STILL won't cycle properly

a. Okay, one more trick to get more bleed gas. Remove the gas plug, piston, spring and tube. put a 1/4" wooden dowel down the barrel.

b. Starting with a #41 or so drill bit insert it BY HAND through the bleed hole in the gas block and use it to determine the size of the gas port hole in your barrel.

c. Once you have determined the approximate diameter of your gas port hole, take the next larger drill bit and use it to ream the hole out. Keep the drill speed slow and use plenty of cutting fluid and you will be less likely to break your drill bit off in the hole.

d. Test the function of the rifle once you have gone up a couple of sizes. You should see some improvement. You can increase the size of the hole up to about 0.125" untill you get enough gas for proper operation.


8. Bolt closes easily on headspace guage but will not chamber round. Jams up tight.

a. Does a cartridge fit into the chamber when you feed it by hand?

No. Clean chamber thoroughly. Ensure cartridge is in spec. Lastly, you may need to ream the chamber slightly.

Yes. It could be the top rear edge of the bolt binding up against the top inside of the carrier. Put a piece of Playdoh or some other putty on the inside top rear of the bolt carrier and then put the bolt in the carrier. Put them both in the receiver and try to push it closed with a cartride in the bolt until it binds. Pull the bolt and carrier out and observe the Playdoh. Is it pinched all the way to the carrier? If so, file a small amount off the top rear of the bolt until it clears.

 

[dsol]

Checkout falfiles.com, there is a wealth of information there on this exact same problem. I had it myself with the same rifle. Mine will work with inch or metric mags (inch cut receiver) after I did a little polishing and reshaping the rails at the bottom of the receiver. They were rough and sharp on the bottom, polished those up and widened the opening a little, polished the feed ramp and it runs like a champ.

 

[Robert Richardson]

Open up the rails above the mag lips,contour them to match the mag lips.Century receivers need a few little modifications to run right.Also make sure the mag lips are smooth and the bottom sides of the rails are smooth and dont have any sharp edges.Look on the falfiles,do the mods and it will run fine.

 

[Robert Richardson]

What did the smith do to the mags?

 

[sporter]

It may also need some polishing of the feed ramp. The Century receivers are quite tight as far as tolerances go from my experience. I would grease up the receiver and bolt rails to help it cycle smoothly.

The US made barrels also have very tight chambers on the century guns and it could also have a burr on the edge of the chamber as my century did. This can delay ejection and cause jams.

 

[Indiana]

Sorry, meant failure to feed. The bolt carrier will extract the spent cartridge, but doesn't seem to have enough force to chamber the next round and then go into battery. Could it possibly be a spring issue?

Where is your gas adjustment nut currently set? It sounds as if it is slightly short stroking, which could be rectified by a click or two on the gas adjustment nut right behind your front site. A little more gas pressure will push the bolt back faster and it will return with more force.

 

[Haans]

Where is your gas adjustment nut currently set? It sounds as if it is slightly short stroking, which could be rectified by a click or two on the gas adjustment nut right behind your front site. A little more gas pressure will push the bolt back faster and it will return with more force.

I think it's currently set to 0 actually.