I bought a former police SP1 with a 1968 serial number.  Still has the edgewater buffer( yesssss) a newer CS marked A1 length A2 type stock and a replacement M16 bolt carrier marked with an N with an early chrome gas key ( no step), MP marked bolt.
 National Aerospace was the manufacturer of the carrier from what I found, but I can't find anything else, like years used etc.  Anyone have any info?

 
 

dont know anything about it, but it is cool!  Also very cool there is a 601 full round gas key on it.  Cant wait to hear more people chime in.

BCG is quite the eclectic mix of parts. Can’t say I’ve seen a 601 key mates to a modern contract carrier before. Bolt is from a GM Hydramatic M16A1. Standard late pattern firing pin, cam pin.

Thank you.  It was supposedly from a PD in Puerto Rico.  I figure stuff got mixed up in the  Arms Room over the years.  

I was to understand the N marked carriers were contact units made by Smith Enterprises. Navy contract according to some stuff I read.

I used mine in my NASA rifle so now the N means NASA

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