Can someone please tell me the diameter and length of the pin that goes into the safety selector from the rear of the ar-15, I took a buttstock off and, well I found the spring but the detent was no where to be found. I figured I would make one out of a drill bit shank tommorow at work, but I need the dimensions. SO if any one happens to have one within easy reach, will you please measure it

thanks in advance.

The pin that goes in from the rear goes into the takedown pin not the selector. If the takedown pin will not come out the detent my still be in the hole. Heres is a link to all of them. The shape of the end of the pin makes all the difference wether it will work or not.
www.biggerhammer.net/ar15/pins.html

I had the same thing happen the spring shot out, I was sure the pin did too. A closer look revealed that the pin was still in the hole.