In the last article, we covered a variety of topics about the ACOG and its benefits and failings. The ACOG is not perfect, but it is a great general purpose optic that offers great low light performance. This article will address some of the various 4X models (not all of them!) and make a point of highlighting the application of each model. Keep in mind that my data is merely a rough estimate as your conditions and mine are likely different. Caveats: I am shooting in YARDS, and most ACOG’s are calibrated to METERS, so I am attempting to fit the BDC into a civilian friendly setup. Note that some of the data will be different due to the various loadings, errors in my use of Strelok, etc. but to the best of my knowledge, the below will help you choose a BDC and ACOG that will suit the role well.
Bend the Curve: The ACOG BDC
Let’s start with the beginning. The TA01. The original. El Primo. The TA01 is calibrated for a 55-grain bullet traveling at 3250 FPS while mounted to the carry handle and is supposedly calibrated for Meters… BUT WHY DOES IT FIT SO WELL FOR THAT LOADING IN YARDS!? I don’t ask questions, I just do what Strelok tells me to. So it’s calibrated for an antiquated rifle length system shooting an antiquated cartridge. Since we are civilians, I am happy to share that a 20-inch rifle still works fine and 55-grain bullets still hurt. It’s not the visual hotness of an 11.5 suppressed mk12, but I assure you that a rifleman can score positive hits out to 600 with 55-grain bullets. This guy right here has done it. So what other loadings can we fit into this model?
M855 is within a few inches of the BDC and it’s a good fit for the TA01. Also, Black Hills 77 TMK @ 2750 mirrors the M193s trajectory out to 600 yards quite well. There we go, that’s a modern loading! So the TA01 fits in a unique niche, it can handle very fast, light bullets such as M193 and then it can also handle bullets with a very high BC and still be a good fit… At least to 600 yards.
The TA01 model is a great all-around optic for a rifle length platform. There is no reticle bloom so precise shots are easy, and the tritium is often noted to be brighter than the fiber optic models. I suspect this is due to issues where bright tritium might illuminate the fiber optic.
The thick crossbars also make it easy to center your target when looking out from a dark area into a bright area. The fiber optic models have a more minimalist reticle design which is an Achilles heel in such conditions.
Very much aligned with the TA01 is the B model which is calibrated for .308 rifles firing military ball. What’s nice is that it matches Black Hills 77 slightly better than the TA01 especially at the 600-800 yard range but they are largely interchangeable. A miss wouldn’t occur simply because your BDC was 5 yards off at 500 yards…
Otherwise, the TA01B will work fairly well with all the above loadings, but the BDC leans more to the mid-weight to heavyweight 5.56 cartridges.
TA31 series (NOT F) follow the same BDC as the TA01, save for that these models are all fiber optic illuminated with a variety of reticle choices. These are solid optics, but with washout from indoor to outdoor and weapon light shooting… Dual illuminated models are not my favorite.
The 31F is the flat top, carbine blend of the TA31 series calibrated in METERS. It is a poor choice for rifle-length systems as M193, M855, and 77 TMK do not match the BDC well… in yards or meters. To get a good match for yards, you need to drop M193 down to 2950 fps… Velocity typical of a 13-14 inch carbine. M855 needs to be slowed down to around 2750 fps, typical of around a 12-inch barrel. 77TMK needs to run at 2500 FPS to match well enough to 700 yards… Again velocity closer to a 14-inch carbine than a 16 or 20-inch gun.
I owned a 31F based on the advice of others (“it’s good all-around” they said!) but it was a poor fit and I had to make derpy 60 grain reloads to fit the BDC out of a 20-inch gun. Couple this with the difficulty finding the reticle with a weapon light, or from indoors to outdoors. I sold it. Quick.
The TA01 NSN matches well with the velocities of the cartridges above. It’s best for shorty pistols in the 12-14 inch range when shot in yards. When used for a 14.5-inch carbine, the M855 BDC will be a perfect match in meters at 2970 FPS. Just as it was designed.
The ACSS Reticle:
It appears to be, literally, an M855 BDC from a 20-inch gun rifle length system. Its a nearly PERFECT match in yards. This means that the heavier TMK77 grain will be a great fit like the TA01B, with a looser fit towards the lighter M193 loading particularly as we push past 600 yards.
WEW. Lot’s to digest there. Do we need part 3? It took me a while to map all those 4x models out, but I can share my thoughts on some of the other models if TRIJICON will help me out. There are a variety of other models available and darn its hard to keep track of the ACOG Lineup. I truly appreciate the ACOG and find more satisfaction with it than my Razor HDII I owned. It took me a while to feel out the various models, having sold off two simply because the minimalist reticle design is not my favorite. The lightweight, excellent low light performance and bright tritium illumination make me a fan. I suspect the price to value ratio is what has allowed the LPVO to overtake the ACOG in popularity. Nevertheless, ACOG’s are still valuable tools for the Rifleman and can offer solid performance out to as far as the ACOG eye can see. If you can’t afford one, consider Primary Arms line of ACSS optics to keep you on target.
If you liked what you see here, please consider supporting the blog by purchasing an ACOG from our site sponsor Brownells, it won’t cost you extra, but the small percentage we get will help keep me, Richard, and D.S. behind the keyboards. Don’t forget to check out the GG&G line of ACOG mounts to protect that front and rear lense! (Note GG&G is not a sight sponsor and we will get no$ from purchase through GG&G).
Nice. Thanks for the follow-up. I finally figured out that I have a TA31TRD. Red crosshairs. Crazy accurate. And I actually like the eye relief. Go figure.