I am in the process of gathering parts for my new project, building a correct CAR-15 upper for my 1981 Colt SP-1 rifle. I know that I won't be able to find the correct 1-12 16" carbine barrel, Hoplite and J&T both have new 1-9 Colt barrels for around $250. I have a perfect non forward assist large hole upper that I found at a local gunshow, perfect match to the color on my lower, only it's not marked with "C M" under the rear sight drum, so I don't know if it is Colt or not. I have the correct flat delta ring assem. Did early SP-1 carbines have a 2 position collaspable stock? I am going to purchase a new complete bolt assem, can I use a new style Colt bolt that has the complete rear machined off, or do I need to get a Bushmaster that is only part machined like my SP-1 has now, SP-1 has the older style trigger assem with the small pins like the Bushmasters.
Last question, were the early SP-1 cabine handguards much different than the current production ones, I know the M-4 handguards I have on my Bushy are a much smoother black finish than the factory rough finish.
Thanks
Mark