Been shopping for an ACOG for an Armalite A2 National Match (20" barrel).  I really liked the looks of the Ta31 RCO a4, as it was optimized for 20" barrel, and I like the chevron-type reticle. I was told by a tech rep at trijicon that it would mount right up to the handle, but since optimized for flat-top, the graduated bullet drop compensator would yeild inaccuracies at longer ranges.

My question, will this indeed be very inaccurate at distance? If so, by a lot, or are talking 1/2" or the like?

The TA31 is optimized for handle mounting, but I assume its aptimized for 16" barrel, so it may be inaccurate as well with the higher velocities coming from the 20", and I really didn't want the donut reticle.

Not competing, or setting up a combat rifle, just want decent accuracy out a couple hundred yards.

Thanks, any input appreciated.

Quoted: Been shopping for an ACOG for an Armalite A2 National Match (20" barrel).  I really liked the looks of the Ta31 RCO a4, as it was optimized for 20" barrel, and I like the chevron-type reticle. I was told by a tech rep at trijicon that it would mount right up to the handle, but since optimized for flat-top, the graduated bullet drop compensator would yeild inaccuracies at longer ranges.

The reticle will be different at ranges over 100yds. Changing the height over bore is more important than velocity differences.

My question, will this indeed be very inaccurate at distance? If so, by a lot, or are talking 1/2" or the like?

I have only run the numbers on the older flattop ACOGs which were all designed around the 16" barrel and had both the height over bore difference and lower velocity. On those the difference was several MOA and definitely more than 1/2".

If you really want to know, ask Trijicon for the muzzle velocity, type of ammo (balllistic coefficient), and height over bore that they based the reticle on and you can figure out the exact difference using ballistic software (also available for free online).

The TA31 is optimized for handle mounting, but I assume its aptimized for 16" barrel, so it may be inaccurate as well with the higher velocities coming from the 20", and I really didn't want the donut reticle.

The TA31 and TA31A (triangle) are set up for carry handle mount from a 20" barrel firing 55gr M193 ammunition. If you are really all that concerned about matching the reticle they are your best bets. The donut isn't optimum for precision; but that doesn't mean you can't be precise with it.

Not competing, or setting up a combat rifle, just want decent accuracy out a couple hundred yards.

If you are shooting at less than 300yds practically any ACOG can be made to work...beyond that you'll have to learn to adjust your point of aim accordingly. See the "Big ACOG BDC thread' tacked at the top of this forum for more info.

big acog bdc chart