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Posted: 3/19/2005 5:16:56 AM EDT
[Last Edit: Zhukov]
Link Posted: 3/19/2005 5:17:35 AM EDT
[Last Edit: Zhukov] [#1]
Link Posted: 3/19/2005 5:18:07 AM EDT
[Last Edit: Zhukov] [#2]
Link Posted: 4/8/2005 2:25:24 PM EDT
[Last Edit: sovereign] [#3]
From a phone conversation with Trijicon to confirm the BDC specs, I was told the following data were used to develop the BDC:

Flat Top Models:

14" barrel, 62gr., 3050 FPS

Carry Handle  Models:

20" barrel, 55gr., 3120 FPS



Link Posted: 4/8/2005 5:40:04 PM EDT
[#4]

Originally Posted By sovereign:
From a phone conversation with Trijicon to confirm the BDC specs, I was told the following data were used to develop the BDC:

Flat Top Models:

14" barrel, 62gr., 3050 FPS

Carry Handle  Models:

20" barrel, 55gr., 3120 FPS




Hmmmm, odd that Trijicon is managing to get about an extra 80fps out of their 14.5" barrels according to the info they gave you. Looks more like they really did calibrate it using a 16" or even 20" barrel.

When the chart was put together, we had no input from Trijicon beyond the fact that the F-series were designed for 62gr M855 from a 14.5" flattop and the rest were for 55gr M193 from a 20" carry handle. I used the normal average velocities for these rounds from those barrels to compute the BDC chart.

Anybody who would like to redo the whole chart using the new values is most welcome to do so, but I think most people will find the differences to be pretty minimal.
Link Posted: 4/8/2005 6:54:28 PM EDT
[#5]

Originally Posted By Bartholomew_Roberts:

Hmmmm, odd that Trijicon is managing to get about an extra 80fps out of their 14.5" barrels according to the info they gave you. Looks more like they really did calibrate it using a 16" or even 20" barrel.




And they must be using IMI M193 out of the 20" barrels
Link Posted: 4/9/2005 6:29:47 PM EDT
[#6]
Looks like they used SAAMI 55gr .223 since I show better velocities than that for a 20" firing M193.
Link Posted: 4/11/2005 2:06:03 AM EDT
[#7]

Originally Posted By Bartholomew_Roberts:
Looks like they used SAAMI 55gr .223 since I show better velocities than that for a 20" firing M193.



I get @3,130 out of my 20" with IMI M193. I've seen others mention the same here.
Link Posted: 4/11/2005 3:32:57 PM EDT
[#8]
I notice several questions regarding zeroing the ACOG at shorter distances.

Here are the aim points at 100, 200 and 300m on the ACOG. On the donut, this is top of donut, middle of donut, bottom of donut. On the chevron, this is top of chevron, bottom of chevron point, and small illuminated portion of ladder below the chevron. Triangle is tip of triangle, middle of triangle, bottom of triangle (see a pattern here?).

Actual zero range is 25yds = zero as above using 300m reference as point of aim
Actual zero range is 50yds = zero as above using 200m reference as point of aim

If you are attempting to zero using the charts above, you will also need to convert to MOA and adjust your point of impact accordingly. Example:

For a Carry Handle 16" or 14.5" firing M193 but zeroing at 50yds:

Normally, you would sight in .25" low at 100m and be 1" high at 200, 2" high at 300 and 400 and then within MOA out to 600. Since you are sighting inat 50yds, you take the difference at 200 (0.5MOA) and apply it at 50yds (1/4" high above your 200m point of aim).

As always, these are rough estimates designed to get you on target quickly. You should always verify the zero at the appropriate ranges in the environmental conditions you plan to use the rifle in.
Link Posted: 5/22/2005 5:28:30 PM EDT
[#9]
I need some help.

Here is my set up (may be not tactically correct...)
TA11, flat top, 11’5 barrel (1/9) and 55gr FMJ, mostly .223.

What will be the best zeroing distance? How to use my BDC?
Every advice, including another choice of ammunition, will be appreciated!
Link Posted: 5/23/2005 8:47:18 AM EDT
[Last Edit: Bartholomew_Roberts] [#10]

Originally Posted By JohnParis:
I need some help.

Here is my set up (may be not tactically correct...)
TA11, flat top, 11’5 barrel (1/9) and 55gr FMJ, mostly .223.

What will be the best zeroing distance? How to use my BDC?
Every advice, including another choice of ammunition, will be appreciated!



All you need to figure this out is a ballsitics calculator and some basic information (muzzle velocity, height over bore, weight of bullet and ballistic coefficient).

Here is a link to a good online ballistics calculator.
www.norma.cc/htm_files/javapagee.htm

You can probably find the average velocity for 55gr from an 11" barrel at The Maryland AR15 website. The rest of the information you need you can pick up from reading this thread. Let us know what you find out.
Link Posted: 6/1/2005 1:52:10 AM EDT
[#11]
I would like to know about the findings of the TA11 on the 11.5" upper. I have a TA11 on a BUshmaster 11.5" Flattop upper. Been using it here in Iraq for the last 9 months.
Link Posted: 6/16/2005 11:26:35 AM EDT
[#12]
So how do you range find at those distances with the ACOG. I mean how do you know your target is at 500 meters etc?  
Link Posted: 6/18/2005 1:31:40 PM EDT
[#13]

Originally Posted By Creeper:
So how do you range find at those distances with the ACOG. I mean how do you know your target is at 500 meters etc?  



The raning stadia bar on the reticle - the width of the bar is aprox the width of a human chest at that range.  - Dump a few rounds - if he is still kicking - add or drop as required.
Link Posted: 9/18/2005 11:58:52 PM EDT
[#14]
.
Link Posted: 10/12/2005 11:55:53 AM EDT
[Last Edit: IBTLplus1] [#15]
Nevermind.
Link Posted: 12/30/2005 8:47:20 AM EDT
[#16]
How far off is a TA11, when used on a FAL with surplus ammo, say Port or Aussie? I'm trying to figure out if I should sell it and get a TA11C -
Link Posted: 3/14/2006 9:59:45 AM EDT
[#17]
.
Link Posted: 4/11/2006 7:30:05 PM EDT
[#18]


just in case
Link Posted: 10/18/2006 10:16:19 PM EDT
[#19]
68gr and .308 reticles may or may not follow. I need muzzle velocity for the 68gr load out of 14.5", 16" and 20" barrels and I need to know the round used to calibrate the .308 ACOGs, we are guessing M852 match right now - if correct I still need a muzzle velocity for it out of a 20" barrel.


I'm shooting the 68gr BTHP Canned Heat out of a 16" Flat top, if I can find sombody with the chrono I will get it as this would be great as I want to replace the aimpoint with an Acog.
Link Posted: 10/24/2006 9:15:36 PM EDT
[#20]
Where does the TA31RCO-M4CP fit into this equation? Do you know if it is compensated for 62gr? Why does it say 16" on one page of the Trijicon site and 14.5" on another, is the difference that small?

Product Link:
www.trijicon.com/user/parts/products1.cfm?PartID=481&back_row=1&categoryID=3
Link Posted: 10/25/2006 8:07:55 AM EDT
[#21]

Originally Posted By jdmpimp:
Where does the TA31RCO-M4CP fit into this equation? Do you know if it is compensated for 62gr?


The TA31RCO-M4 uses the same BDC as the TA31F. It is set up for 62gr.


Why does it say 16" on one page of the Trijicon site and 14.5" on another, is the difference that small?


I have no idea why it says that on the Trijicon web page; but the difference is that small.
Link Posted: 10/30/2006 1:08:55 PM EDT
[#22]
did I i miss this or is it not there - a TA01 on a 14.5/16 inch carry handle firing M193.... ?  (I see there's 855, but not 193)
Link Posted: 10/30/2006 4:47:26 PM EDT
[#23]

Originally Posted By chapperjoe:
did I i miss this or is it not there - a TA01 on a 14.5/16 inch carry handle firing M193.... ?  (I see there's 855, but not 193)


Sight in as normal. The only difference is a slightly lower muzzle velocity which doesn't make much difference until you are way out there.
Link Posted: 10/30/2006 5:04:50 PM EDT
[#24]
Thanks for the repost, Lumpy! I had almost forgotten about this post. I hadn't referred to it since I first installed my ACOG a while back.
Link Posted: 10/30/2006 5:22:19 PM EDT
[#25]

Originally Posted By Bartholomew_Roberts:

Originally Posted By chapperjoe:
did I i miss this or is it not there - a TA01 on a 14.5/16 inch carry handle firing M193.... ?  (I see there's 855, but not 193)


Sight in as normal. The only difference is a slightly lower muzzle velocity which doesn't make much difference until you are way out there.


but what about my 1200 yard shots with 55 grain ammo?
Link Posted: 2/25/2007 8:19:29 PM EDT
[#26]
I have a TA11F that's going on my Noveske Afghan upper.  How would I zero it to best accommodate Black Hills 75gr. ammo (blue box)?
Link Posted: 2/27/2007 10:11:04 PM EDT
[#27]

Originally Posted By chapperjoe:

Originally Posted By Bartholomew_Roberts:

Originally Posted By chapperjoe:
did I i miss this or is it not there - a TA01 on a 14.5/16 inch carry handle firing M193.... ?  (I see there's 855, but not 193)


Sight in as normal. The only difference is a slightly lower muzzle velocity which doesn't make much difference until you are way out there.


but what about my 1200 yard shots with 55 grain ammo?


chapper.....Awesome post count for 2 years, brother. Impressed! (compliment BTW)

INCIRLIK
Link Posted: 3/1/2007 8:48:17 PM EDT
[#28]
height=8
5.56mm Carry-Handle BDCs...

Stats used to figure BDC baseline:
M193 traveling at 3,259fps with a BC of .243 and a height over bore of 3.5"


height=8
62gr. 5.56mm Flattop BDC...

Stats used to figure BDC baseline:
M855 traveling at 2,970fps with a BC of .304 and a height over bore of 2.5"


Where did the height over bore values come from?  I can't seem to verify these numbers anywhere.

Thanks,

Mike
Link Posted: 3/1/2007 9:37:01 PM EDT
[#29]

Originally Posted By VortecMAX:
Where did the height over bore values come from?  I can't seem to verify these numbers anywhere.


They came from measuring from mid-objective to the middle of the bore with a tape measure. You don't have to be real precise since you need fairly major changes in height over bore (0.5" or so) and fairly long ranges before it becomes an issue.
Link Posted: 3/1/2007 9:51:24 PM EDT
[#30]

Originally Posted By swenis:
I have a TA11F that's going on my Noveske Afghan upper.  How would I zero it to best accommodate Black Hills 75gr. ammo (blue box)?


Not enough information to tell. You need to know height over bore (2.5" for a TA11 in a TA51 mount), ballistic coefficient of the 75gr Hornady, and muzzle velocity from the Afghan barrel. Also, I don't have the time anymore to figure out that data for everyone who wants a specific match for their rifle; but I can tell you how to do it yourself.

When you have all those things take a ballistics computer and enter the info from "Stats used to figure BDC baseline" for the ACOG of your choice (For the TA11F, it would be M855 traveling at 2,970fps with a BC of .304 and a height over bore of 2.5"). Assume a zero of 100yds. Note the rise/drop every 100yds or 100m. You can do more if you like; but all you are doing is describing points on a parabola for comparison.

Now enter the data from your Novseke Afghan into the ballistics computer. Adjust the zero range on the ballistics calculator until the trajectory best matches the data you have written down for every 100m. You are unlikely to get a perfect match and you may have to decide whether you need a greater match close-in, or a greater match at distance. When you have a zero distance that gives you a trajectory you can live with, note the rise or drop at the range you will physically zero the ACOG (for example say 1.2" high at 100yds). When you go to the range, adjust your ACOG until you are striking 1.2" over the point of aim (which should be the outside tip of the chevron for the TA11F).

Here is a handy online ballistics calculator if you don't already have a program:
www.norma.cc/htm_files/javapagee.htm
Link Posted: 3/1/2007 11:48:37 PM EDT
[#31]
Im running a TA31F on a 20" A4gry using XM193 on a 50/230 zero. Ive worked out the true values for the BDC. If anyone else is running this combo let me know and I'll post it up, otherwise I'll continue to be a lazy Mofo.
Link Posted: 4/19/2007 7:40:15 PM EDT
[#32]
Any Data on firing a 6.8 SPC round vs a 5.56 & 7.62 calibrated ACOG?
Link Posted: 6/27/2007 6:45:30 PM EDT
[Last Edit: GlockSlap] [#33]
I changed my bal. coefficient to .362 per sierra website, and saw a big benefit...

Anyone work out the math, hard data for an 11 inch with 77 Mod 262 travelling 2400-2450 FPS...?

I played with the calculator using a 3.5 line of sight on my TA31DOC but I'm not sure what effect it has POA/POI.  I guess I just want to try and line up the BDC even if just remotely...

At 100 yard zero I'm getting a 3.9 inch drop at 200 yards, and -17.1 inches at 300 yards, and 42.4 inches at 400 yards.  Here it is making 402 bs of energy. At below 1800 FPS, the 77 SMK loses some efficiency, and BC becomes .343.  These figures allow for that.

Link Posted: 9/8/2007 7:29:27 PM EDT
[#34]
Any testing with BH blue box v max 60 grain with acog tao1nsn bdc?

Any testing with 68 grain HMHP
From black hills blue box?

I am searching for best bdc round for 1-7 and 1-9 twist barrels.
Link Posted: 11/18/2007 1:17:34 PM EDT
[Last Edit: EricCartmanR1] [#35]
Awesome info!

I have found you can use any ACOG for any rifle as long as you know your rifle and the ammo it uses.  Even if you have and exact match of reticle and rifle type, such as a TA01NSN, shooting M855, out of 14.5" barrel... you are still going to be a little off due to variances in ammo, humdity, elevation, etc.

For me I am using a ACOG TA11F (designed for M193 out of AR flatop) in my .308.  I know I am basically:
- dead on at 100
- half a head too low at 200
- one and a half heads too low at 300

- When I use the 400 yard BDC at 400 yards, I will be 1.5 heads too low
- When I use the 500 yard BDC at 500 yards, I will be about 40" too low (about the length of your crotch to tip of your head)
- When I use the 600 yard BDC at 600 yards, I will be about the size of a short human (~60 inches) too low.

It gets me close enough
Link Posted: 12/4/2007 10:52:31 AM EDT
[Last Edit: chapperjoe] [#36]
So the TA11C would probably be the best choice for a flattop 18" 1/7 with 75gr ammo right?



.308 Carry-Handle BDC
This BDC is based on a carry handle ACOG firing M852 Match out of a 20" barrel.
ACOGs using this BDC include the TA11C and TA01B.
snip
For a Flattop 16" firing 75gr OTM @2615fps
Sight in at 100 per manual. This is a real close match. Max deviation is 2" at 600m and you'll be within 1" at all other ranges.
snip
Link Posted: 1/12/2008 11:50:48 PM EDT
[#37]
I have a TA50-4 compact, mounted on my carry handle, 14.5 barrel.

Anybody know what numbers I would have for what height the optic is above the barrel, and what the numbers shoulod be that I would zero in on ?
Link Posted: 3/16/2008 11:30:02 PM EDT
[Last Edit: WhisperPickle] [#38]
nevermind
Link Posted: 3/24/2008 2:37:48 PM EDT
[#39]

Originally Posted By underdog75:
Im running a TA31F on a 20" A4gry using XM193 on a 50/230 zero. Ive worked out the true values for the BDC. If anyone else is running this combo let me know and I'll post it up, otherwise I'll continue to be a lazy Mofo.


I'd like to see this. Please post underdog75.
Thanks.
Link Posted: 4/4/2008 6:22:16 AM EDT
[#40]
I see there are examples for 16" flat tops.
The TA01 NSN is calibrated for a 1/7 and my BM is a 1/9.

What rate of twist were the examples given?
Is it worth me buying a RR 1/7 16"

Thanks.
Link Posted: 4/8/2008 1:15:58 AM EDT
[#41]
tag!
Link Posted: 4/15/2008 6:50:17 AM EDT
[#42]
I have a TA31F and I shoot 62gr cheap ammo but it does the job.. it is on a flat top 16" barrle.. Im just wondering how that will do.. it seems pretty good but I was just wondering if you have any pointers and another thing is how do I use the Chevron I know the top point is 100m but what is 200 the bottom of it or the inside of it.. and then there is this other line that goes down to the 400 I was wondering is that for the 300? if you can help me that would be awesome.. Im pretty sure it is top 100M then 200M is right under the point and the 300M is the line? cuz after that it goes right to the 400M line..

Thank's
Link Posted: 4/20/2008 2:48:20 PM EDT
[Last Edit: Raven6] [#43]
TA33R-8 Comp. 3x30mm ACOG & 10.5" upper?


What would be the best distance to zero this optic on the MK18 mod 0 upper? Will be using a LT mini ACOG mount. Can someone run the data for me using M855? Any advice welcome



Rangers Lead the Way!!


Raven6
Link Posted: 4/30/2008 8:24:11 PM EDT
[#44]

Originally Posted By Rigamortous:
Any testing with BH blue box v max 60 grain with acog tao1nsn bdc?

Any testing with 68 grain HMHP
From black hills blue box?

I am searching for best bdc round for 1-7 and 1-9 twist barrels.





I dont know if this will help anyone but...

I use the ACOG TAO1B which is calibrated for  308 168  ammo at around 2600fps
when put on a A4 with 20 inch barrel and using black hills or handloads at 2600-2700 fps the 77s match the TAO1B BDC perfectly all the way out to 800 yards and works with the 68-69s to
if you use m193 it is good out to about 600 and about the same with m855  they are not exact but you can hit a half man target
Link Posted: 5/6/2008 6:26:08 PM EDT
[#45]
Any way to calculate (or has someone measured) the BDC values for the ACOG TA33-8.  What I'm after is what are the drop values off of line of sight for each hash mark?  I would like to take this and try and work a load backwards from a ballistics program in an attempt to load up something that would work with the BDC.  So if you are 0" at 100, how many inch drop does the reticle represent at 200, 300, 400, 500, 600 meters.  Thanks for any info or direction!
Link Posted: 5/11/2008 3:07:43 AM EDT
[#46]
I have found the TA31RCO-M4 uses the same BDC as the TA31F with 62gr. even tho the TA31RCO-M4 says it is for the 14.5 inch it will do better on a 16" barrel so if you are going to buy a TA31RCO-M4 due to the fact you have a 14.5 inch barrel just go for the TA31F it is cheaper and the same.. I use a 16" barrel and I have a TA31F and I love the thing.. best optic I have ever owned and seen.. I just don't get Trijicon saying the bdc is for the 14.5 (for the TA31RCO-M4) when it is the same BDC as the TA31F.. with my Armalite 16" using 62gr. I am right on the BDC.. I find I do pretty good with 55gr. also but the 62gr. seem's like it is made for it.. just letting people know so they don't spend the extra cash on the TA31RCO-M4 on there 14.5 when they can get the same with the TA31F.. it also will do good on a 18"
Link Posted: 5/19/2008 7:36:54 AM EDT
[Last Edit: M4A1OwnsYou] [#47]
Thanks for the writeup!  I was concerned about being able to use a TA01NSN/TA31 on my M4gery and M16A4gery.

Where do these hit roughly at 50 yards?
Link Posted: 5/19/2008 11:07:37 AM EDT
[#48]
I am a little unclear on the bottom line.  If I have the USMC 4x acog on a 16" AR, would I be better off using 77 grain Sierra Match Kings or 69 grain Sierra Match Kings to approximate the trajectory of the 62 grain green tips.

From the above I am concluding it is best to zero about 1" high at 100 yds with either ammo.  Please correct me if I am wrong about that.

Thanks!
Link Posted: 6/6/2008 12:27:12 PM EDT
[#49]
Can someone explain to me how to understand the different types of bullets, like 855 193, etc?   It is confusing me....
Link Posted: 6/11/2008 3:23:13 PM EDT
[#50]
M193 =  Older USGI standard issue (Vietnam era till early 80s), 55gr Full Metal Jacket Boat Tail loaded to 5.56 NATO chamber spec

M855 = Current USGI standard issue, "green tip" 62gr Full Metal Jacket Boat Tail with Steel Penetrator loaded to 5.56 NATO chamber spec.  Bullet is designated SS109.

BH 77gr SMK OTM = Mk. 262 = Black Hills 77gr Sierra Match King Open Tip Match (white box), loaded to 5.56 NATO chamber specs.  Current issue with some units in theater.

Have a nice day.  
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