A friend of mine who works for the Florida State Patrol recently traded some Colt SP-1’s to a large gun/ LE distributor. They are now being listed on Gunbroker. If someone really wants an SP-1 it may be worth looking into.
The AR-15A2 was the first A2, had a Gov’t profile barrel in 1/7", with case deflector but A1 rear sights. Should also have the A2 buttstock and A2 forend.