ACOG Questions


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Bazooka Joe71
March 15, 2008, 01:27 AM
So I bit the bullet(no pun intended) and bought an ACOG. I got a lightly used TA31F with an ARM's #19 quick detach for $750.00 shipped, so I thought it was a pretty darn good deal.

I did a search, maybe I'm just stupid, but I couldn't find all the answers I was looking for...

1. After reading this (http://afsf.lackland.af.mil/DefChal/2002/M4%20ACOG.pdf) it says to use the 300m crosshair at 25m to zero it for 300 meters...Where is the 300m mark on the Chevron reticle? I'm not sure if it is at the bottom of the triangle(at the top of the post) or if it is at the tip of the triangle.

2. What is the tip of the triangle zeroed for if the answer to question #1 is at the top of the post?

3. How high will the bullet be @ 100m using a 300m zero

4. What is a killflash good for? I understand what it is used for, but is it worth ~$30.00? Can you see that honeycomb pattern while looking through the scope?

5. Finally, and I know this is something I should know, but how far off will the #'s be using yards instead of meters? I'm still pretty new to the magnification game and could use tips for all of my magnified optics.

I'm sure I will have more dumb questions to bug you guys with later, but this will do for now.:D

Thanks, answers are greatly appreciated as always.

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taliv
March 15, 2008, 01:37 AM
1. you're using the wrong instructions. for the ta31f 100m is tip, 200m is inside top, 300 is bottom, even with the illuminated uppermost part of the vertical post.

4. you cannot see the honeycomb while looking through the scope.

5. close enough for gov't work

Coronach
March 15, 2008, 01:39 AM
4. What is a killflash good for? I understand what it is used for, but is it worth ~$30.00? Can you see that honeycomb pattern while looking through the scope?Killflash is good for preventing the objective lens from reflecting sunlight back at a downrange observer. Unless you plan on using this as a combat gun, you don't need it...but it also doesn't really hurt anything to have it. It does block a small percentage of light from coming into the optic, so the sight picture is slightly darker- and by slightly, I mean imperceptibly so...it might make a difference in low light applications, but probably not even then.

You won't see the "honeycomb grate" through a magnified optic. You can see it if you have an unmagnified optic, but only if you focus on it instead of the target (it will blur and fade out if your eyes focus downrange). It can be an issue if you have a 1x optic and are using the iron sights to shoot through the optic, as focusing on the FS is close enough that it can bring the honeycomb back into focus a little.

Mike

Bazooka Joe71
March 15, 2008, 02:26 AM
Thanks for the help!

1. you're using the wrong instructions. for the ta31f 100m is tip, 200m is inside top, 300 is bottom, even with the illuminated uppermost part of the vertical post.


So if the tip @ 100m is zero, where do I aim at 25 m to zero it? What is the "inside bottom" and what is the "bottom?" Sorry, I'm a bit confused.

5. close enough for gov't work

Unless you plan on using this as a combat gun, you don't need it...

Nope, you are talking to a armchair/gun range comando here.:p

but it also doesn't really hurt anything to have it.

With that said, I'll probably eventually pick one up for for S's and G's.:)

BTW, I was just messing around with the rifle(triple checked and unloaded) outside while smoking a ciggy and I was looking through the scope into the dark at various distances and now I understand what you guys mean by good glass. I am amazed at how clear and deep I can see into a somewhat wooded area when looking through this thing.:what:

Everything is just so crisp and clear! Without even firing a shot, I can tell I am going to have 10x more fun with my AR now that I have an ACOG on it.

taliv
March 15, 2008, 02:35 AM
http://www.trijicon.com/parts/ACF59.jpg

not sure how to explain this any other way. the lowest edge of the legs of the chevron on the right and left are the "bottom" :) and the "inside bottom" is the lower side of the center of the chevron.

hope that makes sense. if it doesn't, i'll have to break out ms paint and draws some arrows on that pic


edit: btw, yeah, it's nice glass. you get what you pay for. take care of the glass. keep it covered when not in use.

post edit: iirc, bartholomew has a sticky around here somewhere with all the aiming comparisons for different loads (M855 vs M193) on various acogs that I believe he originally posted to arfcom. ask if search doesn't turn it up

Bazooka Joe71
March 15, 2008, 03:08 AM
OK, how you described it, this is how I took it...But it seems like the "bottom inside" is the 400m mark, so I guess I'm still confused.:o

I really appreciate the help...Dumb guys like shooting too! LOL

I guess I am confused, because between 100m and 400m, I don't see a distinct 200m and 300m.

http://i64.photobucket.com/albums/h200/benrulez71/chev.jpg

And you are welcome for the top notch art work.:p

taliv
March 15, 2008, 03:13 AM
no, see if this is helps:

btw, is your reticle a triangle or a chevron?

Bazooka Joe71
March 15, 2008, 03:18 AM
post edit: iirc, bartholomew has a sticky around here somewhere with all the aiming comparisons for different loads (M855 vs M193) on various acogs that I believe he originally posted to arfcom. ask if search doesn't turn it up

I will definately check that out...Not that I'm a good enough shooter to see a difference.

no, see if this is helps:

That is exactly what I needed.

btw, is your reticle a triangle or a chevron?

Chevron...I just threw that together in the generic paintshop from windows...It doesn't have a silhouette though.

I was just confused because the distance between 100-200 and 200-300 is so much different.

Oh, and BTW, the bar from the bottom of the triangle legs to the "4" is also red unlike the drawing you showed, not that it matters.

Bazooka Joe71
March 15, 2008, 02:20 PM
One last question...

In the PDF is says:

Using a standard DOS target or a computer produced 25m target, center the 300m crosshair in the hollow center of the small black boxes and fire one 3 shot group.

So if I wanted to zero it for 100 yards, I'd use the tip of the chevron?

How high at 100 yards will I be if I zero it for 300?

Thanks...I know these questions have been asked before, but I've already got a thread going.:)

Bartholomew Roberts
March 15, 2008, 02:46 PM
So if I wanted to zero it for 100 yards, I'd use the tip of the chevron?

Yes.

How high at 100 yards will I be if I zero it for 300?

If you zero it at 25m using the 300m aiming point (on the TA31F the top of the BDC post (the tiny illuminated portion) is the 300m aiming point), then it will be dead on at 100m; but you will use the tip of the chevron (the 100m aiming point) instead. That is the beauty of a BDC reticle.

Bazooka Joe71
March 15, 2008, 06:03 PM
That is the beauty of a BDC reticle.


Yes, that is quite beautiful!:D

Man, the more info I am finding out about this, the happier I get with my decision to "bite the bullet" and drop some big bucks(for me, for an accessory) on an ACOG.

Does anyone have any experience with the ARMS #19 quick detach?

I'm just curious as to how well it holds zero when detached and reattached...The crossbar on the bottom of it that fits into the picatinny grooves is slightly smaller than the grooves themselves, so when it is not clamped on tight, you can shift the mount a little forward/backward.

If I make sure that the crossbar is pushed as far back as it will go before clamping everytime, will zero stay the same?

I don't think I will be detaching the ACOG too often, but I do have an ARMS #40L BUIS and I still like practicing with some good ol' irons from time to time.

Thanks for all of the help!

Bartholomew Roberts
March 17, 2008, 04:45 AM
When I ran the ARMS #19S, I had negligible zero shift. Usually too small for me to be able to notice; but sometimes around 0.5MOA. Just push the mount forward before flipping the levers and you should get a fairly consistent zero.

Caveat: when I say it will be dead on at 100m, that assumes that everything else (height over bore, barrel length, ammo type) matches your ACOG. However at ranges under 300yds, the differences are too small for most people to notice unless they start deviating a lot from those numbers (Ex: 16" instead of 14.5", 55gr instead of 62gr - won't see any difference at 100yds. 11.5" using 75gr - you'll see a difference).

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