I considering buying an ACOG due to all the cool pics and talk about them.  I have a Bushmaster A3 Shorty.  It's the 14.5" barrel with the 1.5" muzzle break.  Im pretty certain that I want a donut reticle.  That means I can get the TA31 or the TA11.  But what about the BDC of each one?  I still want to be able to use it without having to adjust for differences.  Now I know the TA31 is calibrated for a 20" barrel, mounted to the carry handle and shooting 55gr bullets.  What about the TA11?  

Calibrated the same.

A 14.5" barrel with the new 75 or 77 grian round mounted directly to your flat top using a TA11 with .308 donut reticle will track all the way out.  There will be of course differences due to the pressure its loaded to but in general its a perfect match.

What about a 55 grain (M193) round through a 14.5" barrel and flattop?  Is there a donut reticle for that?  

For a Flattop 14.5" firing M193:
Sight in per your manual but at 50yds (or sight in 1.5" high at 100m). You'll be high at 100; but virtually dead on until 600 where you'll be 12" low.


This is in the link at the top of the forum.  You should check it out.

Yeah, thanks, man.  I was reading through that earlier today.  I knew that Trijicon has several different models of ACOGs and I was just hoping that one of them was calibrated for a flattop/14.5"/55gr.  I guess not, huh?