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 How do I get this gas block on my barrel?
kcobean  [Member]
8/6/2012 9:51:31 AM
I have a barrel from an old Bushmaster ORC that I want to put a low-profile gas block on so I can install a quad-rail. I got the original FSB off but for the life of me I can't get the new gas block on. I just can't get it all the way onto the barrel. Do I need to freeze the barrel and heat the gas block or something?



The new gas block is held in place with allen screws rather than the pins the old one was held in with. I'm assuming this thing is machined with tolerances intended to keep it in place with just some loctited screws (IOW, it's tight as hell!)

Anyone have any tips?
Hawcer  [Member]
8/6/2012 10:07:56 AM

Be sure to clean off any burrs or raised areas from the pin cross slots on the barrel. You can try warming the gas block too...
Will816  [Member]
8/6/2012 10:20:24 AM
You say the barrel was off the ORC model? Why not just use the shaved FSB that came on it?
kcobean  [Member]
8/6/2012 1:09:14 PM
Originally Posted By Will816:
You say the barrel was off the ORC model? Why not just use the shaved FSB that came on it?


Thought about that, but it has a bayo lug on it and the quad rail won't clear it I don't think.
bellesdad  [Member]
8/6/2012 1:38:07 PM
Are you sure that you are not putting a 5/8 diameter block on a 3/4 diameter barrel?
offroader1006  [Member]
8/6/2012 1:39:17 PM
I would just chop the bayo lug. Having a pinned gas block is worth the extra effort.

If you still want to fit the new one, make sure your gas block is made for your barrel's diameter.
bellesdad  [Member]
8/6/2012 1:41:10 PM
Some gas blocks are manufactured undersized so that they can be opened by a machinist to the exact dimension of the barrel. Check the literature that came with the block and the manufacturer's website.
Gamma762  [Team Member]
8/6/2012 1:47:32 PM
Originally Posted By kcobean:
Originally Posted By Will816:
You say the barrel was off the ORC model? Why not just use the shaved FSB that came on it?

Thought about that, but it has a bayo lug on it and the quad rail won't clear it I don't think.

Hacksaw + file.
WI57  [Team Member]
8/6/2012 3:35:15 PM
Originally Posted By Gamma762:
Originally Posted By kcobean:
Originally Posted By Will816:
You say the barrel was off the ORC model? Why not just use the shaved FSB that came on it?

Thought about that, but it has a bayo lug on it and the quad rail won't clear it I don't think.

Hacksaw + file.


This.

And paint.
JL_2112  [Team Member]
8/6/2012 5:01:29 PM
Originally Posted By Gamma762:
Originally Posted By kcobean:
Originally Posted By Will816:
You say the barrel was off the ORC model? Why not just use the shaved FSB that came on it?

Thought about that, but it has a bayo lug on it and the quad rail won't clear it I don't think.

Hacksaw + file.


Or a Dremel with a cutting wheel... then file and paint.
strat81  [Team Member]
8/7/2012 12:23:57 AM
Try some 400 grit sandpaper on the inside of the gas block. Put a little bit of lube on the gas block when you slide it on.
Fishbone928  [Team Member]
8/7/2012 12:36:57 AM
What exact gas block are you trying to use? If its the VLTOR LPGB, good luck, that fucker is tight. When I was messing with one, I just got a new one.

According to Bushmaster your ORC has a barrel diameter of .750. Is that what size your low profile gas block is meant for?
Everrest  [Team Member]
8/7/2012 1:42:14 AM
On a heavy coated barrel I once used a brake hone to enlarge the hole in the gas block.