Front Sight Assy Straight Pin woes

[Gonz9731]

Greetings haven't posted up in some time, and had to re-register.

I'm having problems with an old Armalite upper. Atthe time (don't know if its current method) Armalite used straight front sight assembly pins in their guns.
Now after removing/replacing the pins for barrel/ rail work the pins are loose; "Falll out" loose.

Anyone experience this?
Anyone advise a remedy?

I thought about having it sent out for taper pin drilling but I'm not sure that's possible, given its already been drilled once.

TIA,

Gonz

[556Cliff]

Yes, it's possible to have it reamed for taper pins, send it to ADCO.

Look here. > https://www.adcofirearms.com/shopservices/shop_qnew.cfm?code=FSB%20Install

[Gonz9731]

Yes, it's possible to have it reamed for taper pins, send it to ADCO.

Look here. > https://www.adcofirearms.com/shopservices/shop_qnew.cfm?code=FSB%20Install

1004 Sir thank you.

[markm]

You can buy the reamer tool from brownells and do it yourself. (never tried this, but this would be the ideal scenario)

[quackhead]

Bravo company has a good deal on taper pins as well- just bought a bunch

[Eric D.]

You can absolutely do it yourself. The BCM pins are great too as they are the correct length and hardness and the heads will not mushroom. A 2/0 reamer is what you need. I think most of them have a square shank at the end so you can use a tap handle to turn it by hand - that part is important. Absolutely do not try to use the reamer in a drill, you will have the holes too deep in a heartbeat. With a quality reamer you will feel it cutting and it won't take much effort, use cutting oil too. I think I got my reamer from MSC Direct for about $20.

The question is how loose your straight pins really are because you need to have one installed to keep the fsb aligned while you ream one hole. Then securely install your first taper pin and ream the other hole. If the pins are so loose that your fsb can rotate even half a degree or so you may have alignment issues so you'd have to use your own judgement on that. Also compare the diameter of your straight pins to the small end diameter of the taper pins. If the straight pin is larger than the small end of the taper pin you might be SOL. Depending on how much bigger the existing hole is you may still create enough taper length for a taper pin to be secure but you'll have a screwed up looking hole on the small side. The key is to go very slowly and use light pressure and periodically clean the hole out completely and check the pin depth - you want to drive the pin in firmly when checking depth to get an accurate reading. Not final assembly firm but enough to know it's not going to go much deeper when you do do the final assembly; you might be surprised how much further you can seat a taper pin with a firm hammer blow as opposed to just your fingers. Once you get close to the depth you want be extra careful as it may only take 1/2 to a 1 full turn of the reamer with very light pressure to get to the finished depth.

This is coming from my own experience of hand reaming pin holes. I had an fsb pinned by adco and while the alignment was good I was not happy with the taper pins they used (too short) so I replaced them with BCM pins and had to ream the holes a little deeper.

[NCHornet]

Because of this I would consider sending it to ADCO.

NCH