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List of FAL Thread Pitches

Rooster

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There have been a lot of members asking for the thread pitch on this screw and that bolt lately, including myself. Another member told me about this page and it is pretty helpful. This is a webpage hosted by another of our members DerbyFAL.

LINK (Administrator note: broken link)
 

Mark_C

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Got a question on the listed threads in the linked table. The table lists the gas tube exterior threads, and the interior gas block threads as 17/32 by 36 tpi. What are the threads that hold the gas adjuster nut onto the gas block?
 

broncdarts

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maybe I missed it on one of the lists, but what is the thread on the gasblock/gas regulator nut? I have an Izzy HB but I think they are the same as the STG-58/G1 etc.
Thanks
 

Frenchkat

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This a reprint of post #39 by Mark in the posted link in this threads post #4.



"There are two, which is the cause for some confusion. The smaller one is a para lower made from a standard lower. That is, 17/32x36, which is the same as a recoil spring tube male thread. The other is a dedicated para lower and is 9/16x32.

They are both slit in a cross and threaded internally for a screw (#12x32, same as a metric front sight) with a tapered head. The tapered head will expand the threads and lock it in place (days before locktite?). They come in both steel and aluminum for both sizes.

This makes removal extremely difficult, and I find a high percentage seized. I can usually remove them by drilling a hole from the front, Then using a standard butstock screw driver, but since its very difficult to get the lower fixtured without crushing anything, I usually have to replace the para bolt. I turn them out of cut-off barrel sections - like 10/22 heavy barrels at .920 OD

__________________
T. Mark Graham the Gunplumber
Arizona Response Systems
16014 West Remuda Drive, Surprise, AZ 85387
Firearm Manufacture, Repair, Restoration, Refinishing.
gunplumber@ArizonaResponseSystems.com"


I also have one of the Sarco Rhody para lowers. It measures out with the 17/32X26" thread.
 

ruarmed

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heres every thing i found in one list

fal
-------------------------------------
Technical: Thread Pitch- A permanent guide (submit changes)
bbl to receiver: 1"x 16tpi, inch and metric; Israeli, metric thread, chase with 1"x16 die.

cross screw for mag release and BHO. 10/32

pistol grip stud/nut 1/4x28 tpi (metric)

inner threaded hole on buttstock double threaded nut (the one that retains the recoil springs) 1/4x28 tpi (all types)

frame lock lever retaining screw (the little one in the back that keeps the lever in) 10/32

handguard screw
It's an 1-1/4" long 10-32 Screw!

Metric FAL Muzzle Threads 9/16-24 L.H.

L1A1 Pistol Grip Screw is a 1/4-28 slotted round head screw 1-1/4" long and uses a lock washer.

Stg-58 rear Sight Screw(s) US 8-36 x 9/16" long

Gas Tube Pin .078" Dia. x 13/32" long (Hint White Painted Coat Hangers are the Right Dia.)

Gas Tube Nut thread size US 9/16-24 R.H.


Metric Front Sight Pin thread US #12-28

Pivot bolt. 1/4x32

Gas block interior, metric and inch 17/32 x 36
Gas tube exterior thread, metric and inch 17/32 x 36
gas tube Rear support, metric and inch 9/16 x 24
Commonwealth front sight #10x40
Return spring tube cap, inside, metric and inch ¼ x 28
Front sling swivel screw and rear sight windage screws #8x40
StG front sight (some variations) #12 (7/32) x 28
Israeli HBAR coupler and muzzle 11/16 x 24
Belgium Long flash suppressor screw (.335" long, .192" slot head) # 8x40

L1A1 wooden grip that holds on the the popcycle stick it's a #8-36 SAE Screw
L1A1 Pistol Grip Screw is a 1/4-28 slotted round head screw 1-1/4" long and uses a lock washer.

hex/allen head screw is also correct. Designation is UNF2A 1/4"x1-1/4". The washer is replaced with "Washer, lock, steel, flat, internal teeth, 1/4" ID x15/32 OD x .026" and goes between the head and the other washer - BA steel #0

inch but screws are 2.5" for extra Long and Long (EL, L) 2" for medium (M), and 1.5" for short (S)

angle of commonwealth front sight is 5 degrees forward

If Ironwood L1A1 then the size is 1/4" x 20 1 1/4"

Rear sight windage screws for both Metric and L1 are 8/36, not 8/40
Co incidentally, the same as AR15 front sight

The pistol grip stud thread and the internal thread on the return spring tube nut (for the screw that holds the butt plate on the wooden stock) on the G1 lower I got from Tapco is 6x1mm. Six mm diameter by 1.0mm thread pitch.
A 1/4-28 UNF nut will screw onto a 6mm stud or screw but it will be quite sloppy.
A 1/4-28 UNF screw will NOT go into a 6mm nut.
The outside diameter of the 6mm fastener is about .015 inch smaller than the 1/4 inch fastener.

Either you have an anomoly or you are measuring incorrectly. the correct size for both on a G1 is 1/4x28 and I have 50 of them here of which I spot-checked ten. all are eaxactly 1/4x28, although a few are dented so threads need to be chased for smooth joining

got hold of a set of thread pitch gauges and checked again and the threads are 1/4-28

gas tube male thread and gas block female thread, both metric and inch 17/32 x 36.

Recoil spring tube male thread is also 17/32x36. The internal, female thread on a recoil spring tube (and the male thread on the plug) is smalle - 15/32x36.

I had to make new screws for the bipod that came on the G1 front end.
Thread is 5/16-24 UNF.

L1A1 Muzzle Threads 9/16x24 RH

the metric hinge pin is 1/4 x 32

the INCH hinge pin is 1/4 x 28

Anybody have the para bolt thread pitch? The bolt that holds the hinge assembly to the lower? It looks like 5/8 inch by 36 tpi. I need to chase some threads.

There are two, which is the cause for some confusion. The smaller one is a para lower made from a standard lower. That is, 17/32x36, which is the same as a recoil spring tube male thread. The other is a dedicated para lower and is 9/16x32.

They are both slit in a cross and threaded internally for a screw (#12x32, same as a metric front sight) with a tapered head. The tapered head will expand the threads and lock it in place (days before locktite?). They come in both steel and aluminum for both sizes.

This makes removal extremely difficult, and I find a high percentage seized. I can usually remove them by drilling a hole from the front, Then using a standard butstock screw driver, but since its very difficult to get the lower fixtured without crushing anything, I usually have to replace the para bolt. I turn them out of cut-off barrel sections - like 10/22 heavy barrels at .920 OD

gas block where the regulator screws 11/16" by 24 tpi

Hi Guys: Just bought a muzzle break for my L1A1. Was advised that it was THE correct one for my rifle but that they were not that common so my plan to simply slot the tube, drill the major diameter a little deeper and tap the pin hole to pull the sleeve tight may not be the best choice of action. My next plan was to buy the appropriate die and thread the muzzle using my angle plate V slot on my drill press and use the spindle to guide the die straight on to th barrel. The barrel OD. is 0.685, if the thread is actually a 9/16 x 24 , then I must assume that the barrel must be removed and turned to the major OD. for 9/16 (0.5325 dia.) x 24 (preferably between centers)and threaded. I will need the rest of the specs (pin size, thread length, tolerances,flat at the bottom of the minor OD, depth, fit, I assume that these are 60 degree V threads), instructions and access to disassembly, etc.) and access to a lathe.
In addition all of these 0/32 threads have me puzzled as I have been a machinist for 25 plus years and have never heard of them. It is a very very BIGGGG world

cross screw for mag release and BHO. 10/32 Is that a #10 x 32 tpi?

Front sling swivel screw and rear sight windage screws #8X40

I'm not sure about the sling swivel screw,
but the rear sight screws are 8x36 TPI.
 
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