AR Sponsor
Bartholomew_Roberts Big ACOG BDC Chart (Page 3 of 3)
|
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! |
|
Originally Posted By Alaskanforfreedom:
Sight in a 100m then add one click up in elevation. Originally Posted By Alaskanforfreedom:
Originally Posted By NUJbrown:
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 |
|
Originally Posted By NUJbrown:
thank you good sir Originally Posted By NUJbrown:
Originally Posted By Alaskanforfreedom:
Originally Posted By NUJbrown:
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. |
In Soviet California, politicians screw you!
|
Originally Posted By Alaskanforfreedom:
Should be close enough out to 600 meters. After that their begins to be a bigger gap. Originally Posted By Alaskanforfreedom:
Originally Posted By NUJbrown:
Originally Posted By Alaskanforfreedom:
Originally Posted By NUJbrown:
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. |
|
Originally Posted By NUJbrown:
thats further than i would ever need a rifle in my ao. Originally Posted By NUJbrown:
Originally Posted By Alaskanforfreedom:
Originally Posted By NUJbrown:
Originally Posted By Alaskanforfreedom:
Originally Posted By NUJbrown:
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. |
In Soviet California, politicians screw you!
|
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?? |
It's like putting on crampons and walking through a room full of puppies.
|
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 |
It's like putting on crampons and walking through a room full of puppies.
|
Originally Posted By FredMan:
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 |
#MAGA Trump/Pence 2016 we did it!!
|
Originally Posted By SuperSet72:
I have height over bore at 2.7" (1.2" from bore to rail + 1.5" from rail to centerline of optic). 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. |
Bartholomew_Roberts Big ACOG BDC Chart (Page 3 of 3)
AR Sponsor
Join the Community
Your next conversation starts here.
Create your free account to join discussions, share your experience, save topics, and connect with the AR15.COM community.
- Join discussions
- Follow topics and replies
- Connect with fellow enthusiasts
Already a member? Sign in
Stay informed by subscribing to our Newsletter