Im having a hard time deciding which Acog I want for my SR-15 Match with 20" barell.Which BDC will go with my 77gr. Match ammo?I will be mounting it to an ARMS #19s.I have my choices narrowed down to TA-01,TA-01 NSN,TA-11,Or the TA-31F.I will only be shooting out to 400 Meters Max.I realise It will take time to find any of these since most are on back order.Any help would be appreciated.Thanks

Check out "The Big ACOG BDC Chart" thread tacked at the top of the forum. It will answer those questions for you; but the short answer is that the .308 ACOG reticle has the best trajectory match to the 75gr and 77gr 5.56mm rounds; but will be useless for lighter 5.56mm rounds.

For a Flattop 20" firing 75gr OTM
Sight in at 100 per manual. You'll be on the low side of the BDC instead of the high side but within 2" or less all the way out to 600.

Is this the answer I was looking for as far as BDC for flat top use?I shoot heavier bullets because the twist is 1/7.7 What Acog is everyone using for their SPR uppers?Ive seen a few pics that appear to be TA-11.Thanks for the info anyway.