installing a used front sight base on a used barrel.

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[ARCHIVED THREAD] - installing a used front sight base on a used barrel.

Posted: 10/31/2014 6:50:41 PM EDT

I purchased a used barrel and want to put an A2 FSB on it. The barrel already had an FSB Installed so it is already drilled for pins.

I searched for an answer, but all I found was drilling barrels for FSB Installation. What do I do if the barrel is already drilled and I do not have the original FSB?

Thanks in advance

Posted: 10/31/2014 7:00:27 PM EDT

[#1]

I would either have ADCO here in Ohio do the work...or drill it for straight pins myself.

Posted: 10/31/2014 7:22:43 PM EDT

[#2]

ADCO

Posted: 10/31/2014 7:37:09 PM EDT

[#3]

That could be tough. Chances are good that the old holes are not in alignment with the new block.

Drilling for new holes may just enlarge the present ones slightly and then all you would have are holes that are now to large to sufficiently hold your sight firmly in place.

ETA: new block won't have any holes drilled in it. Reading comprehension.

Posted: 11/2/2014 12:07:37 PM EDT

[#4]

I've seen where people will drill and tap holes in the bottom of the FSB and run two set screws to the bbl. They seem to hold up ok to light use but I personally wouldn't recommend this. Pinning is far superior IMO. wagonwheel1's advice is gonna be your best option.

Posted: 11/2/2014 12:34:05 PM EDT

[#5]

Has anyone tig welded the holes / slots in the barrel ?

Posted: 11/2/2014 12:40:38 PM EDT

[#6]

.....

Posted: 11/2/2014 10:33:38 PM EDT

[#7]

Armalite makes a clamp on FSB, (it's actually original equipment on their m-15 that have triangle FSB's I've been told).
I'm using one on a .458 Socom and it's been solid.

Posted: 11/3/2014 12:37:23 AM EDT

[#8]

Getting the fsb on against barrel shoulder behind fsb, then welding it on would work, just not look good as if looks would matter. Has anyone done thus?

Posted: 11/3/2014 12:43:03 AM EDT

[#9]

Quote History

Quoted:
Has anyone tig welded the holes / slots in the barrel ?

View Quote

I haven't, but it could be done. If it's not something you could do yourself, you'd probably be better off just buying exactly what you want. Especially in today's market where practically any configuration is available for a decent price.

Posted: 11/3/2014 1:11:22 AM EDT

[#10]

Quote History

Quoted:
Armalite makes a clamp on FSB, (it's actually original equipment on their m-15 that have triangle FSB's I've been told).
I'm using one on a .458 Socom and it's been solid.

View Quote

This or contact ADCO and see what they say. There is really no way to drill a new holes in a new FSB and get them to line up with old holes.

Posted: 11/3/2014 6:22:15 AM EDT

[#11]

2 weeks ago I had the same dilemma and ended up sending it to Adco. Turnaround was quick and it looks like it came from the factory.

Posted: 11/3/2014 10:31:12 AM EDT

[#12]

I built an m16a1 clone and had the big idea of removing the fsb that came with new barrel because I have to have the colt fsb on it. Took me forever to get it on there, pinned, and STRAIGHT. if you don't want trouble, dont fool with it. Its not worth it..

Posted: 11/3/2014 11:08:53 AM EDT

[#13]

For a truck gun from old parts I drilled and tapped all 5 holes in an sight post,used red Loctite on all screws

Posted: 11/3/2014 3:27:17 PM EDT

[#14]

Ive used a new FSB on a used barrel. Using the BRDE jig and a mill. Locate the spindle in the existing groove with just the stripped barrel in the jig then install FSB, drill and ream, repeat on the second groove.

The set up I use.

I've also welded up the used FSB, using a peice of 3/4" OD brass as a backer. Done TIG and MIG. Mig works in a pinch but TIG is better. Both have to be annealed prior to drilling.

Posted: 11/3/2014 7:30:15 PM EDT

[#15]

You should contact John Thomas at Retro arms works. He can also be reached in the retro section and comes with the highest recommendations and endorsements. He has worked on fsb and bbl issues like you are having.

Posted: 11/3/2014 8:24:37 PM EDT

[#16]

Quote History

Quoted:
Ive used a new FSB on a used barrel. Using the BRDE jig and a mill. Locate the spindle in the existing groove with just the stripped barrel in the jig then install FSB, drill and ream, repeat on the second groove.

The set up I use.
http://www.brdengineering.com/images/63628bef35f79d30df6ec4a7c9584164_nx5k.jpg

I've also welded up the used FSB, using a peice of 3/4" OD brass as a backer. Done TIG and MIG. Mig works in a pinch but TIG is better. Both have to be annealed prior to drilling.

View Quote

That's one big ass C-Clamp, what size is that? I think the biggest ones I have are half that size...

Posted: 11/4/2014 9:34:40 AM EDT

[#17]

Quote History

Quoted:

That's one big ass C-Clamp, what size is that? I think the biggest ones I have are half that size...

View Quote View All Quotes

View All Quotes

Quote History

Quoted:

Quoted:
Ive used a new FSB on a used barrel. Using the BRDE jig and a mill. Locate the spindle in the existing groove with just the stripped barrel in the jig then install FSB, drill and ream, repeat on the second groove.

The set up I use.
http://www.brdengineering.com/images/63628bef35f79d30df6ec4a7c9584164_nx5k.jpg

I've also welded up the used FSB, using a peice of 3/4" OD brass as a backer. Done TIG and MIG. Mig works in a pinch but TIG is better. Both have to be annealed prior to drilling.

That's one big ass C-Clamp, what size is that? I think the biggest ones I have are half that size...

I think that's a 6". There is two in the pic.

[ARCHIVED THREAD] - installing a used front sight base on a used barrel.

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