I have a Colt SP1 and it has a screw for the pivot pin. How do I tell if it has a small or large hole? If it is a large hole can I put a small hole upper on it and how and if it small can I put a large hole upper? Where do I get the parts?
Also does it detract from looks that much when you have a Colt Green/Grey lower and a black upper?
Thanks in advance,
The screw type pivot is the large hole front take-down pin receiver.
Bushmaster sells an adapter to allow you to use Small hole uppers on the lower.
Depending on what your plans are for the rifle, Your best bet for a color match is to just use the SP-1 upper and lower, and change out the other parts.
P.S. You could just sell the SP-1 as is ($800-$1000) and use the funds to buy a new rifle.