[B.T.]

I'd use a battle rifle, if I could lay my hands on one. The stopping ability of the larger projectile is the main argument.

The G3 is a weapon, I'm familiar with. Some were used as DMRs. A scope was added, that can easily be removed. The rifle is not as accurate as a sniper rifle, but I think it would be a good compromise. The G3/SG1 even has a bipod on it. If you like, you can attach a grenade launcher underneath the barrel.

If I were serving with an armoured unit, I might use a G3 carbine. Never shot one IRL, so I don't know, if the recoil would be problematic.

I had no trouble entering or leaving the M113 with a G3. A shorter version might be handier, but I never had any trouble with the G3, even in build-up areas or in woods. I think, it all depends a lot on the practice, you had with your weapon.

The differences between G3 and FN FAL/SLR are significant, but I'd still pick one up, if I could not get a G3. The SLR would not be my first choice, though - no automatic fire! It is an option, that is not allways so important, but I'd like the possibility, to do bursts, if the need arises!