If I mill the mag release guard of a new receiver and place a standard upper  with a larg hole of the same size, not a small hole upper  which needs a offset pin like the Colt . Does anyone make a takedown pin like the offset Colt pin but not offset to go in it since there is not detent to hold it?
I hope I explained it well enouh for everone to understand what I ment.

Thanks for any help. Bryan

I understand what you are saying somewhat. You are wanting to mill off the raised fence on your lower. Why not just buy a Colt SP1 lower and be done with it? I aslo think that you have your large/small notations reversed -- more than likely a lower with a raised fence will have a SMALL pivot. Colt made an oddball large pivot that reqired the use of an adapter pin.


Both sizes of the self-captivating pivot pins can be bought here:

www.brownells.com/aspx/NS/store/ProductDetail.aspx?p=17158&title=AR-15+PUSH-BUTTON+TAKEDOWN+PINS