also, some rifles, both 1903 A3 , M1 garand, Krag, 17,s and M14icon,s were and are still being used for Honor guard, salute rifles.
the bolt guns dont need any real modifications, but the gas operated rifles sometime were modified for blank firing.
some of these rifles, are in great shape on the outside, and crusty rusty on the inside.
but then, iv seen them like new inside and out, all depends on how well, and who took care of them.