14.5" AR10 with Trijicon TA11E. BDC Question

[Atlas11B]

So I just got done building my DRD tactical AR-10 which has a 14.5" American defense hybrid weight barrel that has a 1-10 twist and says it's chambered for m118LR round. My question is about using the BDC in the TA11E which has the chevron. Should I be shooting the m118LR ammo, or going with a lighter grain In order to make up some of the velocity that I lost going with a 14.5" barrel. I mostly shoot suppressed out of an omega. I can't find many specifics on the acog calibration but I'm highly doubting it is calibrated for an 14.5" barrel. I'm not looking for precision 1/4 Moa or anything I just want to be able to utilize the BDC all the way out to 600+

 

[j-dubya]

Zero it at distance and then document your holdovers on the reticle as you work you way back in at the closer ranges. Should be real close with that particular Acog you're going to use.

I did this overseas with an extra Mk11 and an Acog that I would tote from time to time. At the time I was using M118LR, and zeroed the 500 meter hash mark at 500 meters and then worked my way back in verifying the difference in dope versus reticle. The difference was negligible at the closer ranges, especially for the size of targets... This was with a 5.56 Acog. I will see if I can find my old notes for that setup.

 

[Atlas11B]

That's a good idea! You must have had plenty of time and a high speed unit to get to test out some spare weapons like that! Jealous. I'm pretty much just looking for minute of man accuracy so just getting good center mass hits on silouhettes will make me happy. We had a trijicon rep on one of our MARF ranges and he told us to just hold that first BDC crosshair on the ta31 right on the poppers belt line and it worked great from the 50-300 yard targets, so I'm sure I'll be able to just play around with the BDC on the TA11 to figure out a similar technique.