NRA/CMP High power mandates loading single rounds in slow fire. (mandates 20 or 30 rd magazine in rapid fire).
so, lying there in Prone at the 600 yd line (left arm in the sling), we pick up one round of .223 loaded with an 80gr match king, loaded much too long to fit in a magazine and slip it into the port where it lies upon the magazine or the single round tray in a modified magazine, I use my pinky to push it just a bit into the chamber. Then we reach thru the handle (my arms are such that reaching over the handle is just a bit more uncomfortable) and press the button to close the bolt, right hand back on the grip, check the wind, focus on the front sight, squeeeeeeeeze, follow-thru. repeat for 20 record shots.
in Service rifle, the AR looks like an M16A2 in .223/5.56 only and has iron sights! Only internal accuracy mods are permitted (4.5lb trigger, float tube, 1/2x1/2 sights, smaller hooded aperture, match barrel).
everything in the gas system, recoil spring, buffer etc must be normal since the rifle is used for either rapid fire or slow fire (2 stages of each in a match).
M1/M1A service rifle shooters and Match rifle shooters with a semi-auto follow a similar process.
3-gun, tac carbine, etc NEVER mess with the above, they load a magazine and run (figuratively & literally)
Poole