Anyone know what size holes are in the the middle of the selector/ Takedown pins on the early M16/AR15?  Going to try drilling them out want to use right size bit. Thanks

Can't answer your question since I've never seen the pieces up close, but I will give you one tip re the selector.

When building up my M16 copy, I wanted all Colt internals, and had a couple of Colt M16 selectors.  Decided to use one as a semi auto type, by cutting off the full auto shoulder, and dropping a small weld bead on each side of the safe/semi detents. When I went to start cutting the shoulder on one, found it was so hard that a file simply wouldn't touch it. The second one, on the other hand, cut perfectly easily.

Have no idea why one switch was too hard to cut, and the other one wasn't, but before you do start dimpling, make sure you haven't got a unit that's too hard.

i have drilled some on the lathe.  i used a #1 carbide center drill and followed up with like a .055 drill bit.  i copied it from an original.  in my findings if you dont have a carbide drill bit your just going to ruin your selector.  they are hard!  i wouldnt even attempt to do one by hand.  from everyone i have had in my hand it is just not a hole.  it has a tapered shoulder hence why i used a center drill.  now i have seen some front pivot pins with just a hole though.  rear pins had the taper.  just my observations but im a machinist.  

Yep. Can't be done with drill and regular bits, or drill press. This selector will not allow itself to be tampered with. Anyone own a CNC machine and want to make a couple of bucks making 60's era selectors?

Quoted: Anyone own a CNC machine and want to make a couple of bucks making 60's era selectors?

There was a dude asking about flat deltas a while back, said he could make some if nobody sold them.. Maybe he can mod slectors for us?? I'll look for his post, and IM him..

I don't think there was a set size or "specification" for the dimples. I have two original selectors with two different size dimples in them. These may not all have been made by Armalite or Colt, there may have been contractors for these as well as other parts.

 Does anyone know what purpose the dimples served?

i too would say part of teh machining process.  the ones i have seen are at a 60 degree angle which coinsides with live and dead centers.  

i too would say part of the machining process.  the ones i have seen are at a 60 degree angle which coincides with live and dead centers.

I know nothing about machining, but I have to ask:
It's been said many times the dimples were for a bullet tip to push the selector, axle pins, and take down pins out during disassembly. Maybe the dimples served 2 purposes? Maybe a coincidence that made machining easier?

Quoted: i too would say part of the machining process.  the ones i have seen are at a 60 degree angle which coincides with live and dead centers.

I'm going to my machinist friends house here shortly. We are going to start the butcher I mean recontouring the receiver. I'm taking a couple of pins and a selector with me.
We are going to start on the receiver tonight. I talked to him today about the pins.
He said he didn't see any problem.
The delay in my receiver reworking has been from him making a jig to hold the receiver.
We are going to make a pattern out of aluminum stock so I can put my A1 back together. This way the rear machining will be repeatable.
Stay tuned we are either going to make some retro parts or mess up some new parts.
Only time will tell.

Elvis

I played with the XM16E1s I saw while at Ft. Lewis. I didn't have the capability to accurately measure the selector dimple but a 2mm allen wrench went in the hole but a 3mm allen wrench would not. Hope this helps some.