So, I helped a customer clean up his SP1 and we are trying to find the year of manufacture. I looked on Colt's site and get 1963, data does not support it. Checked other sites and the serial number just doesn't match up to the years. I'm wondering if they used different numbers on the carbines?

The upper all appears stock, no FA, However, the BC has the notches for the pawl. Unshrouded SA BC. Bird cage FH with lock washer, of course A1 upper
Lower is a slab side with trapdoor stock, old style, definitely not an A2. From pivot is large but has a single pin with detent on the pin.

ser num SP189161

I appreciate it if anyone can point me in the right direction.

Mark