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9/22/2017 12:11:25 AM
Posted: 3/10/2006 7:23:55 AM EDT
I did a search and found a couple things but not one that explained my specific question, so I pose it to you...

How hard is it to install an FSB on a stripped barrel? specifically, to get all the little holes lined up for the barrel, FSB and gas tube. is it made to where it all aligns up by just throwing the stuff on, or is it a pain in the ass series of trial and error?

Thanks.
Link Posted: 3/10/2006 7:40:15 AM EDT
[Last Edit: 3/10/2006 7:41:05 AM EDT by eye_spy]

Originally Posted By FROST18E:
I did a search and found a couple things but not one that explained my specific question, so I pose it to you...

How hard is it to install an FSB on a stripped barrel? specifically, to get all the little holes lined up for the barrel, FSB and gas tube. is it made to where it all aligns up by just throwing the stuff on, or is it a pain in the ass series of trial and error?

Thanks.



As a general rule, it is straight forward and simple.

Though I believe that there are certain makes of FSB's or gas blocks that would have their holes "differently" spaced. So you may have to make certain of the measurement of these when you purchase them.

Gas tubes are more straight forward. All are basically the same and will fit without worries.
Link Posted: 3/10/2006 8:03:42 AM EDT
Need the proper drill size (1/8" or #30 I believe) and a 0/2 taper reamer along with some taper pins.

You will need a way to line the FSB with the alignment pin on the barrel. I use a 8-32 set screw that I drill and tap into the hole above the sling swivel mount. I set it up in a A2 upper that is in a DPMS Panther Claw action block. Then I can align the FSB with the alignment pin and sights on the upper. I use a Ryobi laser to do this.

Once the FSB is set, tighten the set screw down and recheck. Once it is aligned and tight, set it up in the mill or drill press. The bit needs to be square to the FSB. Drill the holes and ream with taper reamer. Drive in the pins.

Link Posted: 3/10/2006 11:37:51 AM EDT

Originally Posted By comp1911:
Need the proper drill size (1/8" or #30 I believe) and a 0/2 taper reamer along with some taper pins.

You will need a way to line the FSB with the alignment pin on the barrel. I use a 8-32 set screw that I drill and tap into the hole above the sling swivel mount. I set it up in a A2 upper that is in a DPMS Panther Claw action block. Then I can align the FSB with the alignment pin and sights on the upper. I use a Ryobi laser to do this.

Once the FSB is set, tighten the set screw down and recheck. Once it is aligned and tight, set it up in the mill or drill press. The bit needs to be square to the FSB. Drill the holes and ream with taper reamer. Drive in the pins.




I think this is WAY beyond what he is asking. Installing the standard FSB on a barrel that has is not drilled for it is one of the most critical and difficult operations on the gun. For this reason, many manufacturers do not even sell the FSB by itself.

A stripped mil-spec barrel should come already drilled for the FSB taper pins. All you'd have to do is fit the FSB, then hammer in the taper pins. The FSB will self-align as the taper pins go in as long as the barrel was drilled properly. Gas Blocks are a bit more complicated as they usually don't use taper pins to secure it, so it won't automatically be aligned with the gas port. You have to do that yourself.

The best way to install and align a gas block that does not use the taper pin indents is the simply use a fine tip marker and draw a straight line from the gas port to the just on top of the shoulder as a target mark. Then do the same on the gas block itself, drawing a line from the gas block hole to ouert edge. Slipping on the gas block, just match up the lines you drew, the one on the gas block to the one on the barrel shoulder and you should be aligned enough for it to funtion properly.

If you plan to use just a standard FSB, I would reccomend if at all possible to get it from the barrel manufacturer. Meaing if it's a Bushmaster barrel, buy the FSB from Bushmaster. If it's a Colt barrel, get a Colt FSB. This way you'll be more assured that the barrel drill work will match the FSB taper pins.
Link Posted: 3/10/2006 11:46:12 AM EDT
[Last Edit: 3/10/2006 11:49:40 AM EDT by comp1911]

Originally Posted By Homeinvader:

Originally Posted By comp1911:
Need the proper drill size (1/8" or #30 I believe) and a 0/2 taper reamer along with some taper pins.

You will need a way to line the FSB with the alignment pin on the barrel. I use a 8-32 set screw that I drill and tap into the hole above the sling swivel mount. I set it up in a A2 upper that is in a DPMS Panther Claw action block. Then I can align the FSB with the alignment pin and sights on the upper. I use a Ryobi laser to do this.

Once the FSB is set, tighten the set screw down and recheck. Once it is aligned and tight, set it up in the mill or drill press. The bit needs to be square to the FSB. Drill the holes and ream with taper reamer. Drive in the pins.




I think this is WAY beyond what he is asking. Installing the standard FSB on a barrel that has is not drilled for it is one of the most critical and difficult operations on the gun. For this reason, many manufacturers do not even sell the FSB by itself.

A stripped mil-spec barrel should come already drilled for the FSB taper pins. All you'd have to do is fit the FSB, then hammer in the taper pins. The FSB will self-align as the taper pins go in as long as the barrel was drilled properly. Gas Blocks are a bit more complicated as they usually don't use taper pins to secure it, so it won't automatically be aligned with the gas port. You have to do that yourself.

The best way to install and align a gas block that does not use the taper pin indents is the simply use a fine tip marker and draw a straight line from the gas port to the just on top of the shoulder as a target mark. Then do the same on the gas block itself, drawing a line from the gas block hole to ouert edge. Slipping on the gas block, just match up the lines you drew, the one on the gas block to the one on the barrel shoulder and you should be aligned enough for it to funtion properly.

If you plan to use just a standard FSB, I would reccomend if at all possible to get it from the barrel manufacturer. Meaing if it's a Bushmaster barrel, buy the FSB from Bushmaster. If it's a Colt barrel, get a Colt FSB. This way you'll be more assured that the barrel drill work will match the FSB taper pins.



You have to drill the FSB and the barrel at the same time as a unit. Yes barrel that was stripped of it's FSB will have the channels cut but a new stripped barrel won't. It would be super difficult to match a blank FSB to a barrel with the taper pin channels already there. ADCO does it but that's about it as far as I know. I would not attempt it myself. A blank barrel and used FSB on the other hand I did with some success.

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