looking for some basic info on a possible set up i want to run with . any info would be greatly appreciated . i own a colt le6920 that comes with a 16 in. barrell. i am looking at the acog ta31roc for a scope . my research shows that they make the acog ta31 for a 14.5 or 20 in. barrell . in order to be able to use the sight marks on the rectical as desighned will eather one of these options work . this scope is set up for a possible 800 meter shot . but my guess is that my barrell length will play a big problem on longer range shots . i dont realy want to spend that kind of money and find out i need to change out a barrell to dial in my scope properly for full shot range spectrum . i have taken a look at the eotech as well and think the acog offers me more of what i want . what do you guys think????

That reticule is also calibrated for M855. I have a TA31ECOS which is also set up for a 14.5" barrel on my 16" Stealth. It is close enough for me, I shoot 75gr reloads and not M855 so it would probably be better with M855.

http://www.ar15.com/forums/t_3_18/229420_Bartholomew_Roberts__Big_ACOG_BDC_Chart.html

I'm pretty sure the TA31RCO is calibrated for 62gr M855 ammunition out of either the 16" or 20" barrel (take your pick).

14.5 and 20, the Army version (the M150) uses an average of the two standard velocities.

thanks for the feedback on this post . i probably was not giving enough info on scope . but your post have helped out . the actual scope number is a ta31rcom4 that is set up for a 14.5 barrell. i know i car pull the flash hider and get it down to the correct barrell size . think i am going to try it with flash hider first and go from there . thanks again for your replies

Your barrel is 16.1 inches without the flash hider.  The M4 is for the 14.5 barrel and you arent going to see any noticeable different with your barrel over a 14.5 with m855.  You will still hit a man size moa target to the effective range of your gun and ammo which is what the Acog was designed to do.

Your flash hider has no effect your barrel length. It is 16.1 with or without it.  And if you swap it out or have it cut down make sure you take into account an NFA stamp or pin a permanent barrel extension on it to keep you out of club fed for 10.

ok thought barrel was 16 w/ flash hider and the idea of removing it was to check and see differance if any before purchessing correct barrel if needed. the le model does not have a pinned flash hider .like most other ar,s. i do appreciate you as wel as other members here trying to keep me outa harms way .nice to know there is a lil love out there for a perfect stranger