RCS-- The key thing to remember about the SP1 production is that Colt never, ever throws out good parts if they can be used in civilian production. In the early M16 program quite a few quick changes were performed on the M16 series rifle. The most notable changes where to the upper and lower receivers of the Model 601 was the addition of the forward assist and the captive front takedown pin. These changes provided an unending supply of uppers and lowers for the SP1. Colt found the upper and lower forgings unusable due to these changes. Have you ever wondered why Colt used the early lowers and uppers so long in the SP1? Some changes, little known. When the military switched from the buttstock without the cleaning kit compartment to one with the compartment. The first buttstocks with the cleaning kit compartments had a rubber recoil pad around the compartment. The military discovered that the rubber recoil pad broke too easily and switch to a hard plastic. What do you do with the buttstocks with the cleaning kit compartment and rubber recoil pad? You put them on the SP1. Colt never, ever throws out goods parts.
I had put a current Colt BCG in the SP1 upper, but opted instead for a Stag Nickel Boron BCG I have. Close to "chrome" in appearance. Looks better. May eventually round up a chrome slick side for it to be more 601/602ish.
Here are my "retro" Colt SP1s. The first is done up with Brownell's retro parts into an Air Force Colt 601 with Green Furniture, Triangular Charging Handle, Flat Ejection Port Cover, Duck-Bill Flash-Hider, and Hard-Chromed Bolt and Carrier. The Bolt Carrier should be "Slick-Side", however such retro parts did not exist when I did the build.
The Second is an original Colt SP1 Carbine done up as an Air Force (Son Tay Raider) GAU-5/A/A, the "slick-sided" precursor to the better known XM-177E2. As an SP1 Carbine, it came equipped with the Vinyl-covered Aluminum Buttstock as standard equipment. The Bolt Carrier ought to be "Slick-Side", but no such part existed when I did the build. The Scope is a mint condition, original Japanese "Colt" 3x variant. Note that the use of correct-length 11.5" Barrels is not an issue in Canada as we do not have an "SBR" rule. All AR15s were restricted like handguns up to 2020, when they became prohibited (but thus far retained by their owners).
PM
Originally Posted by imarangemaster
