I've made the decision to equip my Colt Match Target M4 with one of the ACOG TA31s. I see that Trijicon actually makes 3 models of the 31. They claim the 31F is designed for the flattop. Can someone clue me in on what makes the Chevron Reticle more desirable on a flattop? Can the donut (TA31) reticle be used on a flattop? And yes I do plan on mounting the scope to the weaver rail rather than on top of the removable carry handle. Thanks for any info.
--RR

Edit- Also, any info on where to get the best price and quickest delivery would be appreciated.

The reticle for the TA31F is calculated to match the bullet drop of 62gr. M855 being fired out of flattop with a 14.5" barrel.

The reticle of the donut TA31 is calculated to match the bullet drop of a 55gr M193 being fired from a 20" barrel with the scope on the carry handle.



Sure, just look at the thread titled "Big ACOG BDC Chart" to match ammo/barrel/mount to your ACOG.

Bartholomew_Roberts i have a question.My setup is a Ta31f 14.5" barrel 1:9 TA51 mount on a SIR. and most of the time i will be shooting mostly M193,How does the BDC on my ta31f with my steup react ? will it be higher or lower? Im new to this whole thing so bare with me [:D]



Thnx

Every rifle shoot different, you will have to take it to the range & find out how well the BDC works. Elevation & temprature will greatly affect the BDC also...
I find that the Trijicon TA31A works great on a 16" 1/7 flat top with M855.

How do you like the TA31F so far? I'm 90% convinced that's the appropriate choice my M4 (14.5", 1:7) as well. Also, if you found a good price someplace feel free to IM and clue me in.
--RR

I thought the TA31F, TAO1NSN, etc. were calibrated with M855 Ball out of a 16" barrel?
cp

ALL
I just copied this from Trijicons web site, It was located in the FAQ section: I too though that the TAO1NSN and TA31F were calibrated for the 14.5" barrel M4s, Now Im confused.

"What bullet was used to calibrate the ACOG scopes?
The TA01, TA11, & TA31 (.223) was desinged for the 5.56mm, 20 inch barrel, 55 grain bullet, M16/AR15 carry handle mount. The TA01B & TA11C(.308) was desinged for the 7.62mm, 20 inch barrel, 168 grain bullet, M16/AR15 carry handle mount. The TA01NSN was designed specifically for the US Special Operations Command SOPMOD M4 Carbine. To meet their requirements, the reticle bullet drop compensator and range finding stadia lines are based on the trajectory of the 62 grain bullet from a 16 inch barrel, flattop mount (Picatinny rail Mil.Std.1913). "

The stats that B. Roberts posted on the BIG ACOG Chart were based on the 14.5 Barrel.
I AM NOT TRYING TO BURN YOU MR ROBERTS !!!
YOUR CHART IS AWSOME, IM JUST CONFUSED.

I too have seen the 16" on the web page. I always assumed it was a screw up because the owners manual that comes with TA01NSN states it is for the 14.5" barrel. Makes since, as it was designed for the M4.
Thanks.....Chad

I was always pretty sure their optics were either from a 20" carry handle or a 14.5" flat top... Looks like we may need some confirmation one way or the other.

new-arguy and others

My 2nd post/reply above was "cut and pasted" from their web site. But it could be a misprint?
I wander??
cp

I vote for misprint since Trijicon had the eye relief for the TA11 and TA31 reversed on their website for about two years and all of the sights that use the flattop BDC were developed for the M4 carbine.



Check the post I referenced for specifics. You won't see much difference at all inside of 300m. Past 400m, M193 loses its juice very quickly and the drop will be much more than what is indicated on your BDC.