Drilling and pinning A2 front sight

[Bantam1]

I recently picked up a 20" FN barrel and plan to build a new 20" upper. It's just a barrel and has no sight installed. I have been contemplating doing the job myself but am curious about how to keep the front sight from moving on the barrel for the drilling part. I have access to a mill but I don't want to have to make a fixture to hold the sight. I can handle drilling and reaming it for the pins. I watched some videos and it doesn't look difficult. I just don't know how to keep the sight from moving. Would some well taped up vice grips work? The jigs to do this type of work are way too expensive to do a one off job.

The other option is to send it off to have it done for $70 by someone semi local.

 

[B y r o n]

Without the jig(s) to hold things in place the chance of a canted front sight is good. Send it off and have it done right, cheap insurance.

 

[msgriff]

I would send it out if you plan on only doing 1 and don't already have tooling like the taper reamer. If you're going to do it yourself, under the sling swivel is a hole, which is how the gas passage in the FSB connecting the gas port to the gas tube is drilled out. You can tap that hole, dimple the barrel with a jig, and use a set screw. Double-check alignment before drilling/reaming the taper pin bores.
ETA: You have to drill/ream and install the front taper pin, then remove the set screw before you do the rear. The set screw should be a 10-32, so enlarge the hole to a #21 before tapping.

 

[Bantam1]

Cost wise it's making more sense to just send it off. $15 for the reamer, 10-32 tap isn't much but something I probably won't use later, set screw, more labor time...

Thanks

 

[DannG]

I've done a few, one way is to smear locktite on the surface, let it dry overnight, then drill/ream for the pins.
On another, I drilled and tapped the bottom of the sight for a small set screw, aligned, test fired, confirmed zero,tightened screw and installed the pins.
Lacking a fixture, I used a piece of thread to get the front base pretty close, lined up from rear sight aperture, over front sight blade to center of muzzle...
hth.
DannG

 

[Redlion]

I had John Thomas at Retro Arms mount an A2 front sight base on a 16" FN barrel two years ago. Fantastic work. Shipped out on a Monday and had it back in hand that Friday. I want to say that it was around $140 total with shipping and parts supplied.

 

[Bantam1]

The semi local guy is saying he's "months" behind but says I can schedule a walk in because it's a 20 min job. Not sure how the math works if he is so behind but magically I can schedule a walk in quicker. He's about an hour+ drive from me but I would have to deal with L.A. traffic both ways. He doesn't open until 10am either. So easily 4ish hours of driving doesn't entice me to make the drive.

Time to find someone else.