Problem Installing A2 Front Sight / Gas Block

fenceline

fenceline

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So I'm building my first upper. Everything is going well until I get to the A2 sight/gas block. I get the gas tube pinned to it, slide it all on the barrel and realize the barrel doesn't have the cut outs on the bottom to facilitate the taper pins being pushed through. It is a DMPS gov't profile barrel.

Am I missing something here? Do I have the wrong barrel all together for what I'm building???

TIA,
Jay
 
They're normally drilled as a set to ensure fit. You're highly unlikely to find a new bare barrel that's drilled for FSB pins.
 
Each A2 style sight is drill to fit at the factory "so you cant really swap them as the holes may not line up :("
 
I use clamp on A2 sight units on NM guns -- they're even available with bayonet lugs. Check Brownells. Very slight deviation from the normal unit -- and adjustable for left/right to some degree (still need to line up the gas port!!)

For what it's worth - the clamp on units increase the accuracy of teh same barrel compared to taper pins. Not sure why - my thought is that the pins apply some kind of irregular pressure.
 
Sorry - change that. Brownells DOESN'T have them. Armalite part I'm talking about can be viewed:

http://www.armalite.com/ItemForm.aspx?item=EU0240MPKIT&Category=5e96660f-cc85-4db9-ab9d-8a3c238a7007

No bayonet lug, either - it has a sling swivel mount. Maybe not what you want for a C8 clone.

If it is what you want - John Hipwell at Wolverine stocks this Armalite part.
 
Clamp on gas blocks suck. You are better off to go with ones that have set screws and drill in a detent into the barrel and lock tight the set screws in.
 
fenceline said:
By drilling a detent do you mean the groves across the barrel? If so, what is the best way to go about that ensuring the sight block is straight?
Click to expand...

It's not a groove across the barrel. It's a shallow hole perpendicular to the barrel as the set screw is also perpendicular. Any machine shop can drill the groove for a taper pin.
 
Good luck with this whole thing. Drilling after the fact is going to be very difficult. I'll be interested if it's drilled even close to TDC. Let alone taper holes.
 
browningautorifle said:
Good luck with this whole thing. Drilling after the fact is going to be very difficult. I'll be interested if it's drilled even close to TDC. Let alone taper holes.
Click to expand...

Haha, funny, that is what the smith said, almost identically. Anyone know a good source or manufacturer that has A2 style sight / gas blocks with set screws that go up through the bottom? Hoping to find something with a bayo lug for the look I want.
 
Update.... Found these...

Only thing wrong for the look with the Armalite is that it lacks the bayonet lug.

These two companies have front A2 style sights that have alan screws to hold them on... anyone know if the screws are below the profile of the barrel or if the barrel has to be notched for them to work? Or better yet if any CGN dealers bring them in?

Fulton Armory...

AU096.jpg


And CMMG...

CMMG-F-Marked-Match-Triangle-Front-Sight-Base32-2543.JPG
 
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