I'm asking this for my son-in-law. He has a Bushmaster 223 then he bought a Trijicon ACOG TA11-3. Apparently this model is for a 308 rifle. Can he use the TA11-3 on his .223 or does he have to get the ACOG .223 model? ~Thanks folks

He can use it, but the reticle aiming points for 200, 400, 600 and so on, will not calibrate properly for bullet impact at those distances. He'll have to sight it in at one distance and then just guess at the proper hold over for longer distances. Each ACOG (5.56 or 7.62) is calibrated for a certain bullet weight and barrel length. That means you sight it in at 100yds and then the aiming points for the 200+ distances should be accurate. Using the "mix" you mentioned throws all that out the window. It will only be accurate for the initial sighting in distance and all the 200+ aiming points won't be accurate.

Actually if he plans on shooting 77 grain ammo the .308 bullet drop is almost dead on. In fact many guys prefer them for their .223's because heavy bullets are very popular. Pat