All, I have what I think is a simple question about the TA33.  I searched but couldn't find the answer.  Apologies if it's already been answered somewhere.

The 7.62x51 reticle is calibrated using a 175gr. round.
The 5.56 reticle is calibrated using a 62gr. round.

I shoot a 147gr. 7.62x51 round.

When I run these different rounds through a very basic calculator, the 62gr. 5.56 round has closer ballistic characteristics to what I want to shoot (147gr. 7.62x51) than the 175gr. 7.62x51 round.  By that logic, would I be better off buying the 5.56 calibrated TA33 to take better advantage of the BDC?

Thank you in advance!

How would a old ta01 mounted on a carry handel ar15a2 type rifle shooting out to 600 yards with 77 gr ammo?

holyshit this is confusing. if i want to shoot m855 out of a flattop 20 inch gun with a ta31f i should be .8 high at 100m?

Sight in a 100m then add one click up in elevation.

thank you good sir

Should be close enough out to 600 meters. After that their begins to be a bigger gap.

thats further than i would ever need a rifle in my ao.

Yeah me too. Let me know (through IM or email) if you would like to know the data I used to work that up.

OK, after reading all this, doing some hard thinking, and using the Norma calculator, here's what I come up with.

I'm wanting to find the zero so the BDC is as close as possible on my 11.5" SBR, with a TA31F, in a LT100 mount, using XM193 ammo.
Step 1:  Punch in the "standard" data.  62 gr, BC .304, HOB 2.5", MV 2970.  Run the calculator with a zero range of 100m, and find the rise for 100/200/300/400/500/600m
Step 2.  Punbch in the data for my rifle with this scope and load.  What I was able to find is 55gr, BC .243, HOB 2.735", MV 2958.  Run the calculator for a bunch of zero ranges and then investigate the rise at different target ranges (100/200/300/400/500/600)

The following is what I find from the Norma calculator.  To me, unless I've put in bad data, zeroing my setup at 100 or 105 meters is going to make the BDC pretty much dead on.  No variance larger than an inch all the way out to 600 meters.

Am I doing this right?  Is my BC/MV/HOB pretty much right for an 11.5" bbl and the LT100 mount?

OK, fixed the chart.  Got mixed up on my units
11.5 bbl M193 BDC Calcs by FredMan, on Flickr

To my eye, looks like I need to decide if I want:
50 Yard Zero:  1-2 inches high from 100-300, 2.5 low at 400, and 9.5 low at 500 OR
75 Yard Zero:  Dead on to 200, then  1.5", 6", and 15.5" low from 300-500 OR
125 Yard Zero:  Dead on to 200, then 2", 6", 16" low from 300-500

Seems the 75 yard zero is what I want, and to achieve that on a 50 yard range I'd adjust my elevation until my POI is a half-inch below my POA??

New question, how realistic is a MV of 2958 from an 11.5" bbl for M193?  I got that figure from some web site I can't find now.

This post implies that it's really closer to 2884

I think 2850ish to 2900 is more correct but you never really know till you borrow a chronic and shoot some loads

Good info in OP. Thanks

Please keep this tacked.

Well since i dont see any 77 gr. Mk262 data, it was recommended to me by Trijicon to use the TA-11J-308G on my 20" 556 1:7 as they are very close.

Pretty good. Happened to notice in a pretty current USMC manual they took the time to point out to the individual Marine that bore-to-optic centerline is 2.75".

This is an interesting thread, having gone thru my own journey before settling on a TA31-D (BDC is for M193 from a 16" bbl). As others have reported Trijicon was very helpful, if one asks them, in providing the actual BDC calibration info.