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Ghost
September 10, 2017, 18:02
Ok so my search function is weak. Ive found it in the past but cant dig it up now.
I was thinking that the short barrel was 17.25", and cant remember the intermediate length below 21 that was used.
Also I know GP had recommended starting points for gas port sizes on those lengths.

relevant information would be appreciated.

Thanks.

NFADLR
September 10, 2017, 18:07
Original Belgian FN FAL 50.63 Para barrels were measured in mm and there were two lengths.

458MM and another that slips my mind.

Ghost
September 10, 2017, 18:17
Original Belgian FN FAL 50.63 Para barrels were measured in mm and there were two lengths.

458MM and another that slips my mind.

So 458mm is roughly 18.032 inches.

bigstick61
September 10, 2017, 18:40
436mm, which is roughly 17.17".

IMBEL says they use 440mm, which is closer to the 17.3" cited a lot here.

The 436mm length is about as short as you can get a bipod-cut barrel with the sling swivel and combo device fitted to it and be able to use the socket bayonet or rifle grenades. I bought a barrel that someone cut to 17" exactly and it was already too short to use the bayonet with the sling swivel fitted into the barrel.

Ghost
September 10, 2017, 23:52
436mm, which is roughly 17.17".

IMBEL says they use 440mm, which is closer to the 17.3" cited a lot here.

The 436mm length is about as short as you can get a bipod-cut barrel with the sling swivel and combo device fitted to it and be able to use the socket bayonet or rifle grenades. I bought a barrel that someone cut to 17" exactly and it was already too short to use the bayonet with the sling swivel fitted into the barrel.

This is interesting,and the variance between FN and IMBEL kind of explains some of the trouble I've been having nailing down the length. I see 17.1,17.2, 17.25, and 17.3 sited.

gunplumber
September 11, 2017, 08:22
Well, I use 17.2 and 17.3 interchangeably, which may add to the confusion.

I mark at 17.3, and cut outside the line with a 1/8" wide cutter. Rough face on a belt sander to the 17.3 line. Then hand crown so it will fit nicely on the live center for lathe threading. After threading, I move the crown back until the flash hider will time to bottom dead center. So I end up at 17.2. Like a quarter pound hamburger is weight before cooking.

I had a customer once ask for 18" and by an 18 I thought he meant standard generic para length, and by that I thought he meant 17.2. So I made it 17.2 and he wasn't happy - by 18" he meant 18". So I replaced the barrel. Now there are at least 2 states who specify an 18" barrel length in some laws, so now when someone says 18"/para I call for clarification.

In the discussion he wrote this, which I now keep on the page in Stevens book with the Argy barrel lengths, so I can find it at times like these. I have no independent verification of these numbers but it looks good to me.

50:61 533mm/ 21" (20.98")
50:62 458mm/ 18" (18.03")
50:63 436mm/ 17.2 (17.16")
50:63 special order 406mm/ 16" (15.98")

Ghost
September 12, 2017, 13:04
Thank you,
I'm going to go for the 436mm/ 17.2 (17.16") length.

What would the appropriate gas port size be to start at?

When timing the Belgian combo device, what hand tight clock position gives the proper torque when tightened to position?

Thanks

gunplumber
September 12, 2017, 14:21
Thank you,
I'm going to go for the 436mm/ 17.2 (17.16") length.

What would the appropriate gas port size be to start at?

When timing the Belgian combo device, what hand tight clock position gives the proper torque when tightened to position?

Thanks

.116", then move to 3mm if it won't cycle on 3.5

start at the "golden triangle" where the barrel clearance for the gas tube support lines up with the triangular web on the receiver (about 10:30). You may need to creep a little closer to 11 depending on how the hard (how much give) the barrel shoulder and receiver face are.

Ghost
September 12, 2017, 15:12
.116", then move to 3mm if it won't cycle on 3.5

start at the "golden triangle" where the barrel clearance for the gas tube support lines up with the triangular web on the receiver (about 10:30). You may need to creep a little closer to 11 depending on how the hard (how much give) the barrel shoulder and receiver face are.

Im wondering about the timing in the combo device, Is it the same 10:30 as the barrel?

Thanks.

gunplumber
September 12, 2017, 17:31
Im wondering about the timing in the combo device, Is it the same 10:30 as the barrel?

Thanks.

It will need to be hand tight to 15 to 30 degrees short of bottom dead center (bayonet mount).

It times off the muzzle 90 degree face. I use a hand crowning 11 degree which gives crush up to 45 degrees before deforming muzzle.

I'd never heard of, nor seen a part number for factory timing shims until seeing some in Bruce's book (French).

AliYahu
September 12, 2017, 20:14
50:63 special order 406mm/ 16" (15.98")

Thanks for including the 16" - I've been arguing with people for years about the factory 16" guns that were imported for the LEO market 35+/- years ago!

Eli

gunplumber
September 12, 2017, 20:56
Thanks for including the 16" - I've been arguing with people for years about the factory 16" guns that were imported for the LEO market 35+/- years ago!

Eli

I didn't know about it either, until A. Hansen educated me.

Ghost
October 29, 2017, 19:15
What is the gas port size on the 458mm barrels?

I'm just waiting on a thread die holder for the lathe, to finish up my 436mm, but looks like Ive got another in the works.

Thanks

burtman
October 29, 2017, 21:47
Well, I use 17.2 and 17.3 interchangeably, which may add to the confusion.

I mark at 17.3, and cut outside the line with a 1/8" wide cutter. Rough face on a belt sander to the 17.3 line. Then hand crown so it will fit nicely on the live center for lathe threading. After threading, I move the crown back until the flash hider will time to bottom dead center. So I end up at 17.2. Like a quarter pound hamburger is weight before cooking.

I had a customer once ask for 18" and by an 18 I thought he meant standard generic para length, and by that I thought he meant 17.2. So I made it 17.2 and he wasn't happy - by 18" he meant 18". So I replaced the barrel. Now there are at least 2 states who specify an 18" barrel length in some laws, so now when someone says 18"/para I call for clarification.

In the discussion he wrote this, which I now keep on the page in Stevens book with the Argy barrel lengths, so I can find it at times like these. I have no independent verification of these numbers but it looks good to me.

50:61 533mm/ 21" (20.98")
50:62 458mm/ 18" (18.03")
50:63 436mm/ 17.2 (17.16")
50:63 special order 406mm/ 16" (15.98")

My ARS 50:62 is truly my most prized FAL. It has never failed me ever.