Read that as 55K SP-1's made from 1963 thru 1975. The starting serial number for 1976 was SP 55301. Is your serial number preceded with the letters (SP)? If not I'd doubt that it's an SP-1. In my 2nd addition copy the years covered are from 1963 thru 1976. Pics would be of great value here!!!! Scott Duff published a list of SP-1 serial number dates in his book, 'The AR-15 Completes Owner's Guide' in appendix #2. If your barrel is marked 5.56 NATO it is not possible for it to be an early 60's barrel, because the 5.56 did not become NATO standard until the early 80's just before the USMC adopted the M16A2. All of these would be 1-12 twist barrels. Within about a year after that, they started fully chrome plating the bore and those barrels would be marked C MP B (for BORE).Īround 1972 the markings were changed to C MP CHROME BORE. This would be consistent with your early serial number.
#1968 COLT SP1 SERIAL NUMBERS HOW TO#
Colt sp1 serial numbers, did any 1968 colt sp1 rifles come with forward assist notches on bcg, how to read colt serial numbers, twist and serial number sp1.ġ1e40, what are the exact markings on the barrel? C MP C would be a very early barrel, within the 1964-1965-ish time frame when the military was updating to the XM16E1, and would have chrome plating in the chamber only, not the bore.
![1968 colt sp1 serial numbers 1968 colt sp1 serial numbers](https://s3.amazonaws.com/mgm-content/sites/armslist/uploads/posts/2020/01/23/11077282_02_1978_colt_sp1_640.jpg)
Also the serial numbers listed, except for 1963, 1969, 1970, are the serial number at the first of the year. If you see a 1 there, it does belong to the serial number.
![1968 colt sp1 serial numbers 1968 colt sp1 serial numbers](https://www.gunsamerica.com/UserImages/175832/975022921/wm_7345138.jpg)
Note: All SP1 serial numbers start with SP, not SP1. 11e40 and 23eagle, no offense but how do you know for sure your SP1 barrels are 1-7 twist? It's only important because AFAIK that's never been available on an SP1 and if yours truly are original SP1 barrels with 1-7 twist that would be the first I've ever heard of it.