Colt AR-15 ?

[Bitman]

I have an early Colt, AR-15, SP-1, 223 caliber.
It has the chromed lined barrel, but no forward assist.
Could anyone tell me the barrels rate of twist?

[Rick in Oregon]

Bitman: The same rifle I had years ago had a 12 twist. You can easily confirm that with a cleaning rod by marking an index mark on the rod with a Sharpie near or on the handle boss, use a measuring tape and count one full turn. When the index mark comes around a full turn, consult the tape to see how far the rod traveled to make the full turn.