-
If you enjoy the forum please consider supporting it by signing up for a NES Membership The benefits pay for the membership many times over.
first time building an upper from scratch
- Thread starter wiskie762
- Start date
beaker
NES Member
Yea, that is actually not easy. You need to have a jig or tooling setup to do it correctly, or be a pretty skilled machinist to do it without tooling. One of the only things I would have a gunsmith do on an AR. I would use a screw or clamp type of FSB if you can't find someone to do it at a reasonable cost.
I agree with these comments. The alignment is obviously the key. If you decide to do it yourself, using a pair of vice grips to pinch the FSB, where they contact the barrel, can help reduce the likelihood of the barrel/FSB rotating during the process.
I bought a inexpensive"colt" upper kit while back, it came with a new barrel, minus the front sight pin slots and any finish. So I decided to drill and tap the front sight base for set screws.
I started with the hole thats under the sling swivel. You could also drill a hole where the bayo lug is. This got me the ability to lock in place. I then D&T'd the pin holes on the FSB.
Later when I felt all was good I used a slightly undersized drill bit to slightly dimple the barre through the now threaded holes. One at a time. Below is the link I used.
http://gswagner.com/arsight/arsightmods2.html it took me a few trips to the hardware store to get the length right on the screws they are just flush. You can also get a little windage adjustment out of this set up also.
I suppose you could use apropriate bit that will drill flats on the barrel through the threaded holes ? I never got that far.
My friend loved the old colt upper and made a offer I could not say no to. I have not heard a whisper from him about it since.
I started with the hole thats under the sling swivel. You could also drill a hole where the bayo lug is. This got me the ability to lock in place. I then D&T'd the pin holes on the FSB.
Later when I felt all was good I used a slightly undersized drill bit to slightly dimple the barre through the now threaded holes. One at a time. Below is the link I used.
http://gswagner.com/arsight/arsightmods2.html it took me a few trips to the hardware store to get the length right on the screws they are just flush. You can also get a little windage adjustment out of this set up also.
I suppose you could use apropriate bit that will drill flats on the barrel through the threaded holes ? I never got that far.
My friend loved the old colt upper and made a offer I could not say no to. I have not heard a whisper from him about it since.
Last edited:
A screw on will work as a temporary solution, but I would be sure to stake it at some point. A sight held on by tension like that is going to shift eventually.
headednorth
NES Member
- Joined
- Apr 9, 2012
- Messages
- 26,638
- Likes
- 49,145
Last edited by a moderator:
Thank you! Learned something new![[thumbsup]](/xen/styles/default/xenforo/smilies.vb/044.gif "Thumbs Up [thumbsup]")
To elaborate some more.
- The standard A2 Front sight, is usually pinned x2. The cuts in the barrel are called journal cuts.
(I've always called them journal cuts, someone correct me if I'm wrong).
- Then there are gas blocks, that can be pinned. Just what you think. Journal/Drill the barrel - pin through the block and locks the gas block position to the barrel.
- Then you can get a clamp on gas block
- There's also gas blocks that have a set screw on the bottom (or several). Some barrels are pre-dimpled. Others may require drilling a shallow dimple.
