I am going to be sending my lower off to Total Silence to get machined back to pre-A1 specs.  Since I am building a 601 copy, I am planning to go the whole hog and have him drill and pin the buffer tube and make the lower completely slabside and use a ball-detent pivot pin, like the original 601 prototypes.

I made this decision because recently I discovered a new "mil-spec-sized" ball-detent pin offered by Brownells.  It's the second item down:

Ball-Detent pivot pin

Problem though: it appears that the pin has the ball detent almost at the edge, meaning it probably uses the opposite side of the lower to brace on.  However, the original pin had the detent about 2/3 of the way up and engaged a groove on the upper.  I am using an old Air Force upper with this very groove and want it to be right.  Is there a source for the original pin?  Should I even consider this pin?  I will pay any reasonable amount for an original, but if they are just not available, I may consider this option and live with it.

Thoughts?  

The Air Force has a hard time getting replacement pins ! The Ball detent pins suck, the ball either falls out of the pin and you lose the pin or the whole pin falls out and is lost.

The pin in Brownells won't work for what you wan't. You can ask colt who makes replacement pins for the AF or have someone do a fed log search the NSN for them is 1005-00-992-6671.

Did alittle Google, looks like Colt is the current mil supplier for replacement ball detent pins...

Link to NSN info

Quoted: The Ball detent pins suck, the ball either falls out of the pin and you lose the pin or the whole pin falls out and is lost.

FWIW, I have two of these devices installed in two seperate Colt lowers (mine were purchased from DPMS) where they have been for years. Neither have had any of the "problems" listed in these comments.

Mike

Quoted: Quoted: The Ball detent pins suck, the ball either falls out of the pin and you lose the pin or the whole pin falls out and is lost. FWIW, I have two of these devices installed in two seperate Colt lowers (mine were purchased from DPMS) where they have been for years. Neither have had any of the "problems" listed in these comments. Mike

The DPMS pin is similiar but not the same pin were talkin about.
As long as you baby your rifle and keep it in the safe your pins will be fine. Carry it 24/7 in the field, toss it around a truck and take it apart every day cleaning it it and subject your rifle too the general treatment of a military M16 and your pin will come apart. The mil and colt found this out the hard way and thus the detent pin was abandoned real quick and the current style captive front pin adopted....

This rifle is used, but not used very hard.  Not like Pvt. Snuffy would use it anyway.  I'm going for authenticity over anything else.

Thanks for the link.  I'm gonna try and order one tomorrow.  I'm not sure if that place takes orders from "regular joes", but I'll try.  Since it has an NSN number, are there other places I can order it?

Quoted: This rifle is used, but not used very hard.  Not like Pvt. Snuffy would use it anyway.  I'm going for authenticity over anything else. Thanks for the link.  I'm gonna try and order one tomorrow.  I'm not sure if that place takes orders from "regular joes", but I'll try.  Since it has an NSN number, are there other places I can order it?

Colt is real squirrelly when it comes to direct civilian sales for anything , if they won't play, try a licensed Colt dealer/distributer and see if they can order one. You could also try some Class 3 dealers and see if they have any, there are a few legal full auto M16 Mod 01's out there..

Quoted: This rifle is used, but not used very hard.  Not like Pvt. Snuffy would use it anyway.  I'm going for authenticity over anything else. Thanks for the link.  I'm gonna try and order one tomorrow.  I'm not sure if that place takes orders from "regular joes", but I'll try.  Since it has an NSN number, are there other places I can order it?

Did you look on the site Tangeant gave. It looks like they sell things with a credit card. Give it a roll.