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11/20/2019 5:07:11 PM
Posted: 5/24/2005 1:05:47 PM EST
Where can I get a colt front sight base with bayo lug for my blue label 6601 H-bar? Will all colt fsb's tapper pins fit, if made for a H-bar. Who made the bases for colt ? Mine looks like it had the bayo lug milled off.
Link Posted: 5/24/2005 2:10:50 PM EST
Changing a FSB is not a very easy DIY because the distance of the taper pins on the existing barrel have to match the holes distance on the new FSB, which comes without holes.

A competent gunsmith could do this and If you decide to have them do it, ADCO are usually recommended because of their good prices and fast work.

Here's a source for Colt genuine parts.


Specialized Armament (SAW) website link
Link Posted: 5/24/2005 2:34:06 PM EST
Adding: There is no standard position where the holes are drilled and reamed and each barrel and FSB are drilled/reamed as a unit, each being unique unto itself. The chance of swapping a FSB from one barrel to another is very slim, without some type of machining.
Link Posted: 5/24/2005 3:35:42 PM EST
I just wanted to add in my own situation, I changed my upper receiver to an A3 flat top and I had to change to the F type FSB.

I decided to get the YHM flip up FSB with a bayonet lug because it is attached by four machine screws rather than the standard taper pins.

It would be easy for me to install it and adjust and maintain it later on. It's not for everybody but it is one way of doing it.

I wish I was still at my former workplace which have a quick-fix shop for aircraft. My buddies there could rig an aluminum sheet of about 1/8 thick and install a fixed drill bushing and an adjustable second drill bushing. Then just locate the first hole of the FSB and adjust the second drill bushing. Locate and mark the hole pattern, secure the FSB and the drill template and drill the holes.

But the most expensive way is to send it to the CNC jig bore shop.
Link Posted: 5/24/2005 3:39:48 PM EST
I've got a FSB fixture drawn up here at work and I have the pieces/parts roughed out, but my CNC expert went on a month long business trip, so the project is on hold until then.

The job itself is not hard, if you have the right tools to hold the barrel and FSB securely in one spot while drilling and reaming. A stable drilling/milling machine is a must.
Link Posted: 5/24/2005 3:55:15 PM EST
You guys should make a what we call a "drill jig" (DJ).

It could take some time to make it but after it's done you could have a production line going.

It would take a thick base plate of steel or aluminum about .250 to .500 thick with bolted on blocks and thick pins to locate the barrel and the FSB. Large clamps installed on the base plate could be used to secure the parts and drill bushings. Another way is to use bars and fasten them with machine screws to the base plate.
Link Posted: 5/24/2005 3:58:21 PM EST

Originally Posted By Alpha-Romeo3:
You guys should make a what we call a "drill jig" (DJ).

It could take some time to make it but after it's done you could have a production line going.

It would take a thick base plate of steel or aluminum about .250 to .500 thick with bolted on blocks and thick pins to locate the barrel and the FSB. Large clamps installed on the base plate could be used to secure the parts and drill bushings. Another way is to use bars and fasten them with machine screws to the base plate.



What???? Are you reading my mind???? Actually, I made mine out of 3/4" steel and it is adjustable to do all barrel sizes. It holds the barrel on one end by the extension and supports the barrel near the FSB on the other end. That way you can exactly index the front sight post level with the index pin.
Link Posted: 5/24/2005 4:11:41 PM EST
You got it the right way. No I'm not reading your mind it's just standard operating procedure in the aircraft factories where I used to work for about 20 years.

I was a senior tool and manufacturing engineer, my specialty was carbon fiber detail fabrication, sub-assembly and final assembly. But I was also cross trained in tool fabrication, machining, welding, metal bond, sheet metal and other non-metallic materials.
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