What's the difference between the SDM-R and the SAM-R ?

Question

They are both accurised version of the M16, the only difference i know is the action

SAM-R : ROTATING BOLT

SDM-R : direct impingement

Answer 1

Near as i can tell the only difference is in the designation.

SAM-R in the marines and SDM-R in the Army.

They're both based off of AR-15/M16 so they both have a rotating bolt and operate through a direct impingement gas system.

The Squad designated marksman course is run out of Fort Benning and is heavily supplemented by the Civilian marksmanship program (they pay for all the rifles and ammo) and has a lot of civilian instructors from the CMP as well. I'd think they'd provide rifles for both the marines and the army....i've seen people from the navy taking the course but im not 100% sure on the marines.