Gas tube popping out......

[TNRonin]

Ok, I'm working on my G1 franken Para. I had it refinished and the thing looks nice, once I get the elevation issue fixed I'm almost there.

Now for the next issue, the gas tube keeps popping back out of the gas block. It appears the thread edges are getting shiney on the tube which indicated an undersize issue. I have opened the end of the tube a few .000 and it screws in tighter when it bottoms out. I haven't had a chance to shoot it yet to see if this fixes it. Anybody have any other suggestions? I know I'm going to get a larger pin for sure, that can't hurt. I'm also going to chase the threads on the gas block.

TIA

Mitch

[SIG552]

Seems you have it covered although chasing the threads will not add any material on the inside of the gas block. Try another tube (one with good threads).

[TNRonin]

I agree with you on that. My train of thought on chasing the threads was to clean out that phos out of the valleys of the threads. I'm certain that the metal of the tube would not clean out that material and I may actually be compressing the tube against the coating effectively making the thread raceway shallower allowing the threads on the tube to jump.


Err, ya that's it, thats the ticket. LOL.

Mitch

[gunplumber]

G1 gasblocks are predominantly garbage - they are so corroded internally that the threads are too undersized to grip. Changing the gas tube won't help. Need to replace the gasblock or cut the tube short and braze like an StG.

Sorry for the bad news, but when I read the thread title, I said to myself "self, I bet he's got a G1".

[TNRonin]

So noted. How hard is it to change out the gas block?

[gunplumber]

not too hard. drive out the cross pin. then a piece of angle iron between the barrel and block and hammer it off (air hammer works great!). Install new with a piece of pipe larger than the barrel diameter. Use a small pin or allen wrench to make sure the gas port lines up and reinsert pin.

Now on occasion, the holes for the pin won't line up, and thats a real PITA.

DO NOT hammer on the threaded portion as it is relatively soft. Even though the block is bad, they are scarce and someday it may be in need again with a short tube soldered in.

[SIG552]

Gunplumber,

Why are G1 gas blocks generally garbage? I was under the impression that the G1's were made by FN. Or were they negelected after their trip to Turkey? Did the Turks shoot corrosive ammo predominantly?

Thanks,

SIG552

[lew]

Originally posted by SIG552
Gunplumber,

Why are G1 gas blocks generally garbage? I was under the impression that the G1's were made by FN. Or were they negelected after their trip to Turkey? Did the Turks shoot corrosive ammo predominantly?

Thanks,

SIG552

The Turks rode them hard. I'm not sure if they used corrosive ammo, but that's a definite possibility. Someone with more knowledge than I will surely chime in.

[gunplumber]

Its aften used as a deceptive selling point on G1 kits "Belgium Made". Yeah, they are belgium made. then they went to FRG for 6-7 years, and then went to turkey for 30 years where they were ridden hard and put away wet.

As the corrosion is typically in the barrel and gas system and not the netire gun, I suspect it was wet conditions and corrosive primers.