Many rifles for many purposes.
"Knowing what your weapon systems and weapon operators can and cannot do is key to properly emplacement of assets. If you have a Garand shooter that is a tad slow on the reload you might not want him in a support by fire position for a deliberate assault, but flank security would be a good place to provide early warning and slow down enemy reinforcements. If you have an M4 shooter who can't hit the broad side of a barn past 300 meters then a position on the assault team or intermediate support by fire position might be advisable. If you have an M1A shooter all decked out in sniper configuration that can shoot the hairs off a gnats ass at 800 by all means set him up as rear security and as you egress you might lead the enemy into a baited long range ambush."Read more on his Thoughts on the history of military hardware
Get off your rear and get into gear. CPX Foxtrot is coming up. If you're not ready, you'll be at a disadvantage.