Been looking for an armalite clamp on a2 sight but cant find one. I saw a video of a guy who drilled and tapped set screws into a pinned sight.

What's your guys thoughts? Any reason not to? Anyone ever done this?

I have done it several times and it does work. I fully understand that drilling and pinning is the correct, most durable, and accepted way to install an A2 base.

That being said, set screws have held just fine for me.



I have done it with both new and used (previously drilled and pinned) bases and my method works with both. I had a blog post saved that I had been working on for a while that explains the whole process- well at least how I do it. I just finished the post and published it this morning (link below) The biggest problem is worrying about canting the base. Of the several I have done the base was dead on and not canted...and they have not moved since with moderate use. If you follow my instructions exactly, the base will not be canted.



http://acatholicmechanic.blogspot.com/2016/02/diy-a2-front-sight-base-install.html



 

It's pretty standard for match A2's for easier barrel swaps and adjustment of mechanical zero. I use 8-32 set screws in place of the taper pins.

It works best with flats machined in the barrel. Without the flats you won't get full thread engagement in the housing but it will probably still work, just not be as secure.

If you're talking about drilling the underside of the housing the concern would be a bump to the top of the tower imparting enough side force to rotate the housing around the axis of the bore.

That's awesome. I figured it would be pretty simple but your blog is a great resource. I think I'm going to go ahead and do this

Catholicmechanic: That is an excellent post you added, great details and step by step instructions. It looks like what would most likely the best way to add an A2 front sight to a barrel short of getting it pinned.

It seems that the Armalite clamp-on sights are no longer available. I actually emailed Armalite about it, and they stated that it is discontinued. Riflegear.com had a bunch in stock, but is out now. Note that the Armalite sight was not "F marked" height, and the protective ears were not particularly tall. When I used this on 16" mid length builds, the front sight post was flush or slightly above the height of the adjacent ears to zero the rifle.

Dez Arms also makes a set screw front sight for the AR, similar to Catholicmechanic's build, but without the extra set screw through the bayonet lug (which seems like a very good idea to have the extra set screw). JP makes an adjustable clamp on front sight gas block, it looks good but is more expensive due to the adjustable feature.

I really searched high and low to get a clamp on front sight and these were what I found.

Personally, I like clamp on gas blocks, they are easy to install and remove, can be timed perfectly to the rifle, and are reasonably secure. Perhaps not as secure as pinned, but as close as you can get.  It's too bad there are not many options out there.

Absolutely. I'm sure being pinned isn't that difficult, I've never done one but every barrel I see with a pinned sight I automatically feel I have to get a 2 piece hand guard. Also I used the armalight as a sight only for my dissipator with a 12 inch handguard and ran a low pro gas block in the rail. The clamp on was nice for that since where I put it wasn't quite .750 but I was able to tighten it down pleanty still.

 
So this?


http://www.riflegear.com/p-927-armalite-a2-front-sight-clamp-on-w-screws.aspx


(On phone and can't hotlink)

I have built lots of ARs and if your referring to pinning the FSB not being that difficult, well its not easy. Unless you have a jig.

You are drilling into the barrel some and alignment is pretty important.

No that's what I'm saying. Doesn't seem easy. I didn't want to try it while keeping it alligned. Drilling a FSB sounds like a great option

I have done several tapped FSB's  also.  I use a standard 8X32 tap set.  I tap the hole in the base of the FSB and always set that screw first to make sure the sight is on the barrel correctly prior to setting the other screws.  I use cone point  set screws so the screw is less likely to move.
There is a seller on the EE that has been selling F marked FSBs with tap holes for $13 plus shipping.  I bought a dozen from him and have used them on everything from 5.56 to 308 builds without any movement problems. There is also a seller on amazon that is selling the FSB's with set screws installed.
As far as taper pinning.  I still tap the hole under the FSB and use it to establish the alignment of the FSB on the barrel, then drill and pin the front leg of the FSB, then I remove the screw and drill and pin the back leg.  A short screw will plug the hole, and the sling swivel will pretty much cover it anyway.
 
 

JP enterprise makes a clamp on one but they want to much for it IMO.

I ordered a FSB for 13 bucks off brownells and I plan to drill and tap set screws. I'm actually pretty excited about it for some reason lol

Looks like a great option. Gotta keep this in mind if I ever need to do this.

Here's the answer you seek. http://www.amazon.com/dp/B00XIH39RI/ref=wl_it_dp_o_pC_nS_ttl?_encoding=UTF8&colid=1D4KP0UZBLNWA&coliid=I3SRAN9R86AURL

ADCO can mill flats on your barrel for use with a FSB that has set screws instead of pins. (maybe even mod a used barrel that was pinned)

https://www.adcofirearms.com/shopservices/shop_qnew.cfm?code=Barrel%20Modification-Repair

Check with them, they could arrange to drill & tap a new FSB to work with the flats added to your barrel...likely anyway, but talk with them first.