5.56 trajectory Q


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rero360
May 24, 2006, 08:42 PM
I might possibly be deployed to Afghanistan later this year (depends on another unit we are supposed to be back filling) I want to get an ACOG for the mission as while I am no slouch with the iron sights (38 out of 40 on my last qual) I'm absolutely unstoppable with optics.

heres the problem, we don't know what we are going to be issued yet, M4s, M16A2s or A4s. I talked to a rep from trijicon and he said that each ACOG is calibrated for a paticular barrel length, bullet weight and mounting position. my question is this what is the trajectories for a 62 grain bullet out of a 16 and 20 inch barrel? say out to 600 meters.

the main reason why I ask is that I plan on getting a civilian M4gery at some point in the future, and would like to mount the ACOG on that as well, and while I could get a 20" barrel, I'd like to go with the 16" first. If the differences of trajectory between the two isn't major out to 600 meters I'll go with the one I was initialy looking at

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NMshooter
May 24, 2006, 08:48 PM
www.ar15.com

In the optics section there is a tacked thread containing extensive info on this subject.

The short version: probably not too important, depends on what standards of accuracy you are trying to maintain.

blackhawk2000
May 24, 2006, 09:50 PM
http://groups.msn.com/TheMarylandAR15ShootersSite/improvedbattlesightzero.msnw

Read this too.

georgeduz
May 24, 2006, 10:22 PM
well any of those aim point type wont be good for 600 meters,i use the trijcon on my ar i say its good up to 200 meters,it gets on targets fast,and a person at 300 meters is very hard to see.you will be fine but its about 500 dollars.there is not much of a difference 16 or 20 inch barrell ,the trijcon has good adjustments.

pcf
May 24, 2006, 10:58 PM
Don't sweat the barrel lengths, m855 out of a 14.5" or 20" barrel will hit within MOA of the 5.56 ACOG reticle out to 500m. Past 500m Binos and a Radio are your friend.

Here's the important part there are ACOGs for use with a carry handle and ACOGs for flat tops, you can't mix and match these. So if you're carrying an m16a4 don't go get a TA31F and a flat top adapter. Doesn't work out, don't learn the hard way.

Hawkmoon
May 24, 2006, 11:53 PM
I thought the Army was issuing optics. Why do you have to buy your own?

rero360
May 25, 2006, 12:27 AM
I want to go with the TA01NSN, the one with the BUIS on the top, my squad leader has one and used it to great effect in Iraq, it has the line increments instead of the chevron or the donut reticle.

I'm sure some units are issuing optics, but I thinks its mainly a matter of what individual supply chains request for their troops, seeing how it all comes out of class 9 money. I don't know how much money we'll get and what it'll go towards, I'd like to see everyone get M4s and silencers, and optics up to the individual, seeing how everyone is different and one that works for one person might not work for another, like I can use the M68 pretty good, but I don't like to depend on batteries and it doesn't seem to hold zero good enough for me.

As far as the ACOG I'm looking at, my squad leader (former 18B) was telling us that with the ACOG, its not a matter of hitting the target, its deciding where to hit it, you want to put a bullet in the target's heart, no prob, in the head? just as easy. Iknow thats a bit oversimplifing it, but thats idea behind it.

Zak Smith
May 25, 2006, 12:46 PM
There is virtually no difference in the BDC for the CH vs. the flat-top mounted ACOG. Similarly, don't sweat it too much if the model's BDC (TA31, 31C, F, etc) doesn't match the exact barrel length and load you are shooting. A 5000' difference in altitude will change the actual trajectory more than these differences.

Bottom line is that it doesn't make much difference on way or the other out to 200-300 yards, and beyond there, you'll have to verify the come-ups anyway, due to those load/rifle/environmental factors.

rero360
May 25, 2006, 02:24 PM
thanks for the great replies guys, I think I'm going to hold off a couple of more weeks until I know more about if I'm getting sent over or not, I plan on buying the ACOG regardless, but its not a top priority unless I get the mob orders.

Lebben-B
May 26, 2006, 07:31 AM
Here's the important part there are ACOGs for use with a carry handle and ACOGs for flat tops, you can't mix and match these. So if you're carrying an m16a4 don't go get a TA31F and a flat top adapter. Doesn't work out, don't learn the hard way.

The M16A4 has a removable carrying handle. As far as buying a TA01, the BUIS on that thing are worse than useless. Then there's weight. Regardless of what weapon you carry, you'll probably have a tac-light and either a PEQ-2 or PAC-4C on it in addition to your optic. Separatey, they weigh ounces, but put together it adds up to pounds. FWIW, I outfitted my DMRs with TA31s during our deployment.

Mike

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