ACOG BDC reticle measurements

[QuietShootr]

Ok just pulled a bullet. Took all the measurement length, width etc. entered the data into the PDA. With standard station and pressure. I used a BC of .304 and the G7 drag table. mV of 2900fps bullet measured .2225 wide and .905 long.
For a 600m engagement off a 100m zero you will need +4mils or +13.8 moa

What software are you using? I have a full version of Exbal and it gives me similar numbers.

[a0cake]

Guys I'm 99% sure that a .304 BC (G1) is what Trijicon uses. A .304 G7 is definitely not correct, and a .151 G7 is also not meshing with reality. Evidence of this is in the OP's hard measurements of the ACOG's subtensions and my own data, both of which closely align with around a 19 MOA drop at 600M.

[QuietShootr]

Guys I'm 99% sure that a .304 BC (G1) is what Trijicon uses. A .304 G7 is definitely not correct, and a .151 G7 is also not meshing with reality. Evidence of this is in the OP's hard measurements of the ACOG's subtensions and my own data, both of which closely align with around a 19 MOA drop at 600M.

Chit...you're right. I was "doing it wrong".

[a0cake]

Chit...you're right. I was "doing it wrong".

I'm not even sure that I'm right.

Dude this is why I have a strong hatred for M855 and optics with BDC's.

[StainlessSlide]

At the risk of stating the obvious, I think that better measurements can be obtained on the BAC ACOGs by taping the fiber optic to reduce bloom at the 100m mark.

And I hadn't thought to measure the horizonal width of the range lines. *Great idea*.

Doing some trigonometry on the widths at 400m and 500m for the TA11 data, I get .48 meters wide for both, or about 18 3/4 inches.

Man, it's great to actually know this stuff, instead of taking the manufacturer's word (which can be garbled in the passage from Engineering to Marketing).

[StainlessSlide]

I'm looking at the Lake City 62gr FMJBT page of the 2nd edition of Litz's book as I type this, and he gives a G7 BC of .154 for this bullet. The bullet is very long for its weight, so I think it's the M855 bullet with the less dense penetrator.

Putting this into Litz's software with a 59F temperature, 29.92 inHg pressure, 3" sight height, 2930 ft/sec muzzle vel, and 100m zero, I get a drop of 18.46 minutes.

[IndianaBoy]

With my TA33, if I zero with my 75gr handload at 400 yards, it gets me within 2 inches at all ranges with my BDC out to 400. I have chrono data around here somewhere but I'm not sure if it would be useful to you or not.


If I recall correctly, I am then 4 inches low at 500 and ~9 at 600.


It takes a little trial and error, and some work with a ballistics calculator. But you can generally find a usable zero with any ammo from 55gr, to 62/69/75. For me it's not a big deal being 2 inches high at 100.

I appreciate you guys doing the work to discern the finer details of the ACOG reticles.

[StainlessSlide]

With my TA33, if I zero with my 75gr handload at 400 yards, it gets me within 2 inches at all ranges with my BDC out to 400. I have chrono data around here somewhere but I'm not sure if it would be useful to you or not.


If I recall correctly, I am then 4 inches low at 500 and ~9 at 600.


It takes a little trial and error, and some work with a ballistics calculator. But you can generally find a usable zero with any ammo from 55gr, to 62/69/75. For me it's not a big deal being 2 inches high at 100.

I appreciate you guys doing the work to discern the finer details of the ACOG reticles.

Thanks.

I too am willing to use small displacements at closer ranges to improve the long range match-up. Are you shooting at yards or meters?

[ICANHITHIMMAN]

If you're using G7 you need to use a BC of 0.151 for M855...at least according to the data I have. I'm going to stop being lazy and see what that comes up with also.

Ok if I use the G7 BC of .154 I get +11.8 mills to 600m engagement thats only 201.4 foot pounds of energy good thing people are easy to kill.

[a0cake]

Ok if I use the G7 BC of .154 I get +11.8 mills to 600m engagement thats only 201.4 foot pounds of energy good thing people are easy to kill.

Listen man, no offense, but every single set of numbers you've posted in this thread have been way off. Don't know it's your software, bad input, or what, but nothing you're saying is making sense. I would either figure out where you're going wrong or trust my numbers. Anything else is a waste of time.