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12/6/2019 7:27:02 PM
Posted: 3/17/2005 7:48:56 AM EST
I have a cut down m16 barrel (1/12 twist) that has been cut down. I would like to install the standard FSB but the diameter of the barrel is about 0.630".

It is not going to be a primary use site but I would like to use it as a backup.
Is my only option to make 2 sleeves to fit into the FSB and make 0.750" (to fit the FSB)?

Anyone have any ideas?
Link Posted: 3/17/2005 7:56:40 AM EST
[Last Edit: 3/17/2005 7:58:19 AM EST by mr_wilson]
Call Bushmaster and check on the specs for their FSB used on this rifle, maybe they have one that fits your barrel.....


Read the specs there, seems dia is .625 under the FSB on this rifle......

Link Posted: 3/17/2005 8:07:27 AM EST
Buy a shot-out M16A1 barrel from (gasp!) SARCO. The barrel will come with the .625" dia. FSB and the taper pin holes will more than likely line up. Last I checked, Bushmaster was not selling their .625 FSB separately. Even if they did, they would probably be undrilled which would be a major PITA to install unless you are handy with a Bridgeport.


Part# ARO17

You may also try BILLBO in the EE.
Link Posted: 3/17/2005 9:11:10 AM EST
05-0026 - $184.00

PRI Flip Up Front Sight with .625" Bore for the M16 Family of Rifles, Clamp Screws

PRI Flip Up Front Sight w/ .625"" Bore, Clamp Screw Design FUFS-B, Fits Barrels .625"" dia. M16, M4, and

AR15, Eliminates the shadow cast on optical sights mounted on the M16 Flattop receiver, Lightweight

aluminum top post, Low reflection, matte black corrosion resistant coatings, The sight post locks in the up and

the down position, Solid 4140 cast steel base with provision for the gas tube an integral part of the unit,

Accepts any standard retrofit M16 front sight post."

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