The standard 22 inch barrel on the M1A is all that's needed. It works quite well at 1000 yards................and that's with its iron sights.
KEEP THE ORGINAL FLASH HIDER: When using M118 at night, you have no detectable muzzle flash.
The M14/M1A doesn't need to be "tacticool" to work. Keep it simple and it will serve you well.
CPT USAR Ret
USAMU Sniper School Oct '78
Distinguished Rifle Badge 1071