View Full Version : FAL with a fluted chamber

October 02, 2001, 02:32
Does anyone have experiences with a fluted chamber in a FAL ?
The G3 use a fluted chamber and interestingly also the SVT40 which has the same type of bolt as the FAL.
Claus :rolleyes:

October 02, 2001, 06:33
Us reloaders hate fluted chambers. They have a tendency to do bad things to your brass. In theory, I guess the fluted chamber is a good idea, but in practice, I don't see enough utility to justify the extra machining operation. You get enough dirt in a standard chamber rifle so that it won't function, and chances are, that much dirt will screw up a rifle with a fluted chamber as well.

October 02, 2001, 07:43
The fluted chamber is useful on recoil- or blowback-operated systems such as the CETME/G-3.

I think they have little use in a gas operated system that uses the in-barrel forces as part of the unlocking system. The delayed blowback system uses the in-barrel pressure to keep it locked until pressure drops low enough to allow unlocking. The gas systems (SVT, M-1, FAL) use gas to commence unlocking as soon as the projo passes the gas port and the gas expands into the piston spaces.

Different systems require different mechanical interfaces, that's all. The flutes would serve no purpose on an FAL, and therefore designers would NOT add the unnecessarry tool work and time to make them.

October 02, 2001, 07:43
As long as surplus ammo is still available who cares about the brass. I build a G3 kit and have a FA 91. Yes, the brass is dirty and bulged in the flutes. They both work rain or shine, I have had no problems (after tuning the Hesse reciever) with either. My Fal works good too.
I think it is like the Ford v Chevy pickup debate. Both will get you where you want to go, just which one do you say is better? Sorry Dodge owners, they are good too, but I drive a JEEP.


October 02, 2001, 08:43
I've had no problems at all resizing and reloading brass fired from a fluted chamber. The only "damage" is cosmetic. I've had a batch of cases go through three or four reloads. With bottleneck rifle cartridges fired from a semi-auto, I usually toss it after three or four firings anyhow.

And I agree that a fluted chamber would serve no purpose in a rifle with a gas-piston design.

Vanden Berg
October 02, 2001, 08:56
I would agree with EMDII. Fluting the chamber in a gas-operated rifle may actually cause you to lose too much gas, resulting in some ugly cycling problems. If you were to have a chamber fluted, it would probably be best to only flute the portion from where the chamber shoulders down (shoulder meets the body of the case) back. Hopefully the case neck would seal well enough to keep from losing the above mentioned gas. I'm sure that the only cost effective way to have it done would be to EDM the cuts (not to be confused with EMD).

October 02, 2001, 12:11
I was unaware that the SVT40 uses a fluted chamber. I've owned several in the past, but don't have access to one at the moment. I can't think of any reason that it should be fluted. The SVT40 design incorporates a degree of primary extraction and shouldn't need the flutes. Fluted chambers are a necessary fix for some poorly designed guns that lack primary extraction. STG45, CETME, SIG, and HK come to mind. They're simple designs, but won't function with standard chambers. In the past, there have been many guns, mostly machine guns, that used oiled or waxed cases to solve the same problem. The fluted chamber is better in that standard ammo can be used; the waxes and oils collected dust and grit. The point is, the fluted chamber is necessary to make the HK type weapons function due to a design weakness. It would not be some kind of "improvement" you would add to a design that does have a good primary extraction sequence.

October 02, 2001, 14:27
I don't think the SVT has afluted chamber either. But, I don't have one to examine currently. The 2 or 3 I've handled did not have flutes. Either never had them, or got rebarreled.


October 02, 2001, 20:56
I have a SVT 40 and it does, in fact, have a fluted chamber.

October 03, 2001, 01:45
I have seen in a H & K manual that the empty case is pushed out of the chamber - not pulled out. The extractor is only used when the rifle is unloaded.
It's pushed out because of the barrel pressure acting at the bolt head and the bottom of the empty case.
The question is: is the in-barrel pressure when the bolt starts moving higher in a G3 than in a FAL ?
The initial velocity in a G3 with military FMJ ammo is: 2590. In a FAL: 2755 but I don't think the reason is the fluted chamber.
The SVT40 has a fluted chamber. I have seen this in my Tula 1940.
Claus :p

October 03, 2001, 10:07
"The question is: is the in-barrel pressure when the bolt starts moving higher in a G3 than in a FAL ?"

Yes, that's exactly right. The G3 starts extracting immediately. There is almost no delay, and without the fluted chamber to 'float' the case, the extractor will tear thru the rim while the inside pressure causes the case to grip the chamber walls. Most rifle caliber weapons have a built in delay to allow the pressure to diminish. In the FAL, this delay is a combination of the dwell(period of time before the bolt starts moving)and the time it takes the bolt to unlock. By this time, the pressure has been reduced and the case can be extracted. Dwell consists of the time the bullet is in the bore before reaching the gas port and the free travel of the carrier before it starts to lift the bolt.

Difference in velocity can be explained at least partially by barrel length. The G3 has a 17.7" barrel, the FAL barrel is normally 21". There may also be a slight loss due to the blowback action of the G3, in effect enlarging the combustion chamber while the bullet is still accelerating down the barrel. Since the case is free to start moving back, peak pressure is reduced below that of the same cartridge in a fixed breech. The early CETMEs(predecessor to the G3)were chambered for a reduced cartridge with the same dimensions as 7.62NATO to assure proper function. It used a lighter bullet at reduced velocity(140gr at about 2400fps IIRC). As an aside, that's why some believe the Spanish Mausers that were arsenal rebarrelled for .308 are only marginally safe. It's believed they were chambered for this reduced load, not the full power NATO round.

EDIT: It's not so much that the extractor will tear thru the rim without the flutes. As you say, in the delayed blow-back of the HK, the empty case is more pushed out with gas pressure than pulled out by the extractor. What would happen is that the case will grip the chamber walls and the high gas pressure will stretch the case, possibly blowing out the casehead. This is a common occurence with the G3 type rifles when the chambers become very dirty or corroded. The rough chamber defeats the flutes and allows the case to grip. If you're blowing caseheads in a G3, it's a chamber problem. If you're blowing caseheads in an FAL, it's likely defective brass or excessive headspace.

[ October 03, 2001: Message edited by: kev ]

October 04, 2001, 09:46
I have taken a careful look at some used cases. On contrary to what I thought: the cases from a H & K 940 cal. 30-06 are more clearly marked by the extractor than the FAL cases.
Maybe because of the abrupt extraction in the H & K system.
The cases are certainly not pushed out. :confused:

June 04, 2002, 02:09
I plan to convert my FAL from S/A to manually operated. It's difficult to operate the rifle manually. Does anyone know if a fluted chamber would make this easier ?

Texas Jack
June 04, 2002, 09:12
When you say "convert from S/A to manual", do you mean permanently :eek: ? Of course, dialing the gas selector to "zero" will acheive this temporarily... just wondering why you would want this permanent or if that is what you mean.

As to the fluted chamber - I would think that a better solution would be to just polish the chamber thoroughly. A fluted chamber design is intended to allow a dirty chamber to continue cycling - ie: in semi or full-auto modes. Wouldn't really be of any benefit for a manually cycling gun.

There are also a number of other things that you need to inspect that could be causing a rough or difficult cycling - the stock recoil spring could be hanging-up on something. There could be a burr in the action, or something with the magazine, etc.

Others here can help you with this - I am still pretty new to the FAL.

Anyway, please supply more details and you will get more specific help with this.

June 04, 2002, 09:18
Manual extraction with the gas plug turned to "grenade" should be easy. No need to flute.


June 04, 2002, 09:39
Alot of Kaliforny's are doing this. They permanantly disable the gas system.

Claus, you might also try taking out ONE of the recoil springs. You only need enough spring pressure to chamber the rnd as you are not worried about recoil. Some of the guy's also installed a forward assist charging handle as you may need to help push the bolt forward to lock.

Larry aka L/FN

June 04, 2002, 19:04
Claus, are you going to modify your original G1 to this configuration?

June 04, 2002, 21:27
I understand that fluted chambers helps with water expulsion - H & K uses it But then, I'm German - my opinion is probably bias.:D

Para Driver
June 04, 2002, 21:37
We are talking about FAL's, not U-Boats...

June 05, 2002, 03:36
I have a good decent G1 F/A - S/A but I fear next time I shall renew the license to it that the police will demand it's a manually operated weapon.
I have shot it on "G" but I think it's difficult to pull the empty case out of the chamber - especially after the first 3 - 4 shots. A possibility to make it easier could be using a fluted chamber as in the G3 or in the other HK rifles. There must be a reason for the fluted chamber but it has perhaps only importance when there still is a pressure in the barrel ??

June 05, 2002, 03:39
I am sorry - I didn't know the picture was so large

Enquiring Minds
June 05, 2002, 04:48
I will be over there in August... how much paperwork and police harrassment occurs to the owner when a F/A G1 is reported "stolen"? ;)

I really like that Type 2 receiver--made by FN, right?

What kind of scope and scope mount is that?

June 05, 2002, 05:57
Claus, here is a link that does a half way decent job in explaining the HK roller locking mechanism and the fluted chamber...
HK delayed roller locking mechanism (http://user.icx.net/~jonesgil/HKOPER.HTM)

June 05, 2002, 06:56
VERY nice G1.

That is a standard OIP mount and Karl Kapps or Wetzlar/Hensoldt ZF 4x scope. The cat's meow.

The reason for the G3 fluted chamber is to assist primary extraction. Since there is no BC accelerating to unlock the bolt from the LS, the G3 slaps a chunk of momentum into the bolt face. The bolt is held closed by cammed rollers and chamber pressure pinching those rollers. As soon as pressure drops, the cam rollers unlock, and primary extraction occurs based on momentum alone. The fluting gives the chamber a bit of volume into which the brass does not fully flow when fired. You still get pretty striations! Unlocking is a bit easier, although the obturation (sealing ) of the chamber at the case-neck is still tight.

Is why G3 has such a pugnacious buffer!

June 05, 2002, 14:31
Here is the scope from the upper-side.

June 05, 2002, 15:22
VERY nice BGS (Bundes Gruenschuetz, or Border Patrol) Hensoldt/Wetzlar. (sp?)

See if you can resize your pic to 800/640 or so. It'll still display nicely. Use your imaging software on your PC to resize.

VERY nice G1.

June 05, 2002, 23:17
The American company that is making new G3/CETME bbl with the fluted chamber is having alot of FTE problems. I guess they took the cheap way out and did not cut their flutes in the same manner as HK did/does with thier bbls. To have this done to your G1 bbl seems like a real possible goat screw. Hell, better to get a SAKO bolt rifle in my opinon vs. disabling a beautiful rifle like you have there!!!
Gruss Got

June 06, 2002, 11:18
Its really easy to adjust the size of a pictur that is too big for the board.

Just open it in the Windows "Paint" program (its included with Windows 98 and later...under "Accessories" on your program menu).

Then on the pull-down menus, select Image....Stretch/Skew.

Reduce vertical and horizontal the settings to lesser and equal amounts (default is 100%)

This pic is reduced to 33% horizontal, and 33% vertical. Takes less than a minute.

June 06, 2002, 12:33
You could sell it and buy 2 nice bolt guns and not have the hassle, I hate to say it but why bother?????

June 17, 2002, 21:43
related threads merged