Mounting AR front sight

[mousegunner]

How do you install a new AR front sight on a barrel thats already drilled for taper pins?

The new sight doesn't have the holes so how can you drill and line up the holes? Original sight is not available and used ones may not line up correctly.

 

[AccelR8]

I've never done it but I think I would pin the holes in the barrel, then turn (or file if no lathe) the pins down to match the round profile of the barrel, then drill and pin the sight as usual.

 

[Pres100]

How do you install a new AR front sight on a barrel thats already drilled for taper pins?

The new sight doesn't have the holes so how can you drill and line up the holes? Original sight is not available and used ones may not line up correctly.

Not sure what front sight you’re mounting but if it’s not a pin on sight it would be a clamp on sight. Clamps would secure alignment in place of pin. Can’t fathom a sight that is made to slip on a barrel but not clamp or provide ability to pin on…
Can you provide more detail on the sight you have?

Attached is what you need- but I don’t have good dimensions to provide for drilling.

 

[GenePoole]

Midway (and others) sell oversized pins. I've used these before and the results are great. The toughest part is aligning the existing holes with the new holes drilled into the sight block. I use a mill and square up the barrel 90° to the table, then line up the barrel hole to the quill with a 1/8 inch drill rod. Lock the table, affix the sight block, then spot and drill a 1/8 inch hole. Then use the AR sight pin taper reamer to enlarge the hole. Drive in the oversized taper pins and call it a day.

 

[Pres100]

Midway (and others) sell oversized pins. I've used these before and the results are great. The toughest part is aligning the existing holes with the new holes drilled into the sight block. I use a mill and square up the barrel 90° to the table, then line up the barrel hole to the quill with a 1/8 inch drill rod. Lock the table, affix the sight block, then spot and drill a 1/8 inch hole. Then use the AR sight pin taper reamer to enlarge the hole. Drive in the oversized taper pins and call it a day.

Sounds like his sight doesn’t have existing holes….?

 

[Walt Krafft]

I would tap the hole between the sling swivel ears for a set screw. Go sight in adjusting windage by moving the front sight. Then apply wicking locktite to fix the front sight to the barrel. Pins shouldn't be needed.

 

[Pres100]

What will taping the hole between the sling swirl ears for a set screw do? it won't act as a clamp and the set screw won't have anything to mate against.
What am I missing?

I think we need more info on the actual front sight he has ...

 

[GenePoole]

Sounds like his sight doesn’t have existing holes….?

I was assuming so. The ones I've replaced did not have holes.

 

[Pres100]

I was assuming so. The ones I've replaced did not have holes.

Sorry ... I was assuming you were talking about reaming existing holes for oversize pins ... my mistake

 

[GenePoole]

Sorry ... I was assuming you were talking about reaming existing holes for oversize pins ... my mistake

Perhaps I was somewhat unclear. The goal here is to align the mill quill with the existing holes in the barrel, then when you slide on the new sight (which will have no holes at all), the the hole you drill in the sight block will be inline with the existing holes in the barrel. It probably won't be perfect, so you ream a bit oversized with the taper reamer to ensure perfect alignment. That's where the oversized pins come into play.

 

[Pres100]

Makes good sense

 

[GenePoole]

Links:

AR-STONER A2 Front Sight Gas Block Bayonet Lug AR-15, LR-308 .750

The AR-STONER™ A2 Front Sight Gas Block is ready for installation on your AR-15, LR-308 Rifle. Made of steel to strict military specifications,...

www.midwayusa.com

DPMS Front Sight Base Taper Pin Oversize AR-15, LR-308 Matte

Oversize front sight taper pins for realigning and replacing front sight bases. Technical InformationNotes: Oversized front sight taper pin for...

www.midwayusa.com

AR-STONER Front Sight Taper Pin Reamer AR-15

Steel reamer is designed to match the shape of the gas block retaining pin giving a perfect fit. This tool is great for tapering holes that have been...

www.midwayusa.com

 

[Twdmar]

Putting a sight on that's already drilled or drilling a sight for existing pin holes in going to be a little bit of work. Do like Walt says and drill it for a set screw. I might choose rockset over loctite but otherwise his advice is quicker and easier, especially if you don't have a mill.

 

[Pres100]

How does tapping the hole between the sling swivel ears work?what will that do for securing the sight?

 

[Walt Krafft]

The set screw will hold the site and allow you to move it to align it. When you have the gun zeroed glue it with the wicking locktite.

 

[Pres100]

I think I understand what you are saying now ... for some reason I thought you were referring to the "Red" direction to clamp... rather than the "blue" direction which would set it against the barrel.

been a long day .... I should probably stick to liking posts in the "laugh for the day" thread!

Apologies , Walt.

 

[Jeff Porter]

Don't use the existing pin holes. The tower will likely be way out of alignment on the new one. ( doesn't take but 0.006" to move out one MOA). Just use a clamp on front tower. I have even tapped the hole in the blue line in the image above and put a set screw in there.

 

[mousegunner]

Thanks for your replies. I wanted to put this sight


back on to how it used to be. I find used sights with holes and new sights without. Armalite made a clamp on like this but haven't found one yet (discontinued).

I know about tapping holes on the sight and adjusting windage with set screws like White Oak does for service rifles but I don't need that on the M-forgery I'm building.

I contacted ADCO but they couldn't/wouldn't drill a new sight for existing holes on the barrel I'll keep looking for a clamp on or take the barrel to a gun show and see if any used sights kind of line up and take it from there.

 

[akajun]

If you have a mill
Set barreled action at 90* with large end of holes facing up and holes facing towards you
Next stick a drill bit in the chuck and locate the position of both holes relative to two features on the barrel
Next take a rod or pin and put in the chuck
Touch the top of barrel then go down half barrel diameter

Next glue/ epoxy the new front sight on and use the pin in the chuck as a reference on the front sight.
If you feel confident then drill and taper pin ream the fsb using oversize pins

All this is way more work than doing a set screw windage conversion btw but that’s how it’s done

 

[Jeff Porter]

How about a post ban clamp on ? Make me an offer I cannot refuse.