Help with Aimpoint COMP M4 sight

[Agent Smith]

I just received the Aimpoint COMP M4 M68 CCO that I had ordered a little while back, and I kind of figured that just like every other piece of military technology, this would also be for ranges surveyed in meters. I'm kind of stumped how to figure this out so I can use it for ranges surveyed in yards.

The adjustments listed in the manual are as follows:

Each click of the Screw Adjustment corresponds to a 16mm movement of the point of impact at 100 meters, (4mm at 25 meters and 32 mm at 200 meters or 1/2" at 80 yds or 1/2 MOA).

Well, that's all fine and good, but I don't shoot at 80 yards. I shoot at 50 and 100, so I'm having alot of trouble figuring this out. If anybody can help with the conversion for this, that would be much appreciated.

[TonyF]

Originally Posted by Agent Smith

I just received the Aimpoint COMP M4 M68 CCO that I had ordered a little while back, and I kind of figured that just like every other piece of military technology, this would also be for ranges surveyed in meters. I'm kind of stumped how to figure this out so I can use it for ranges surveyed in yards.

The adjustments listed in the manual are as follows:

Each click of the Screw Adjustment corresponds to a 16mm movement of the point of impact at 100 meters, (4mm at 25 meters and 32 mm at 200 meters or 1/2" at 80 yds or 1/2 MOA).

Well, that's all fine and good, but I don't shoot at 80 yards. I shoot at 50 and 100, so I'm having alot of trouble figuring this out. If anybody can help with the conversion for this, that would be much appreciated.

One inch is roughly 25mm. Zero at 50 yards. Each click will be roughly 1/4 MOA or 8mm.

A 50 yard zero will cross sightline / boreline again at roughly 225 yards. Bottom line is with a 50 yard zero you can hold dead on from 25 yds to 225 yds. From 0 to 25 yards you need to learn diminishing holdover.

[Agent Smith]

Perfect! Thank you so much.

[625]

Perfect! Thank you so much.

Please post feedback on that sight. I'm looking to get that exact one. Let us know how you like it! Thanks.

[soberbyker]

Originally Posted by TonyF

One inch is roughly 25mm. Zero at 50 yards. Each click will be roughly 1/4 MOA or 8mm.

A 50 yard zero will cross sightline / boreline again at roughly 225 yards. Bottom line is with a 50 yard zero you can hold dead on from 25 yds to 225 yds. From 0 to 25 yards you need to learn diminishing holdover.

Just got my first rifle a few weeks ago, not up on the lingo, what is "diminishing holdover"? The only range I've been to so far is only 55 feet (18 yrds) long, my sight is on target for that distance.

Thanks in advance for your help,
Bill

[TonyF]

Originally Posted by 625

Please post feedback on that sight. I'm looking to get that exact one. Let us know how you like it! Thanks.

If I may, purchase an Aimpoint M4 without apprehension or hesitation.

[TonyF]

Originally Posted by soberbyker

Just got my first rifle a few weeks ago, not up on the lingo, what is "diminishing holdover"? The only range I've been to so far is only 55 feet (18 yrds) long, my sight is on target for that distance.

Thanks in advance for your help,
Bill

Specific to AR15's (and AK's) there is approximately a 2.5 inch offset between the sightline (iron sights and properly mounted optics) and the boreline (recall how tall the front sight base is on AR's and AK's).

What this means is that no matter what distance your AR15 is zeroed, at point blank range the POI will always strike about 2.5 inches below your POA.

With an AR15 zeroed at 50 yards, the trajectory and POI at 25 yards will be about one inch low which for all practical purposes at COM is negligible.

The closer you get to 0 yards, the lower the POI will be until it ultimately reaches the 2.5 inch difference between the boreline and sightline. This is why holdover diminishes that farther you are from the target.

So, if you're zeroed at 50 yards, POA = POI. The closer you get to the target, your POA (or holdover) has to be higher.

I'm sure you've heard of "kentucky windage"? This is a.k.a. "tennessee elevation". It WILL make a difference for precision shots at close range.

The closer the optic or iron sights are to the boreline, the less holdover is required.

[27hand]

Bill,

I replied earlier but my server went down so here it is again.

Let me preface the answer with this.

When a rifle is zeroed at any distance(lets use 100 yds), the bullet will cross the point of zero twice. Initially the bullet is going upward and will cross the first zero point. It will then drop and cross that point once again(which is the zero point).

The bullet will only hit the zero point perfectly twice in it's flight path.

Tony is using an AR to reference his response but it applies to all rifles to varying degrees.

Diminishing holdover is where the bullet position is relative to the distance from the barrel out to the first zero point.

Example with an AR rifle.

The iron sights of an AR are 2 1/2" above the boreline of the barrel.

When you line up the sights and press the trigger, the bullet hits the first zero point (bullet rising)at 25 yds.
It will be 2 1/2 " low at 10 yds so if you want to make a precise hit at 10 yds, you must actually aim 2 1/2" higher.
At 15 and 20 yds, the bullet is still climbing so the holdover is less. At 15 yds, you may have to hold over 1 1/4 to 1 1/2 " and at 20 yds, the diminishing holdover may be about 3/4" ( these are examples as I haven't done the actual holdover amounts with my rifles).

What Tony is saying is that a 50 yd sight in will allow you to aim dead on and be assured the bullet will hit reasonably out to 225yds (which is the second zero as the bullet is dropping)

I hope this is clear.

later, edit, I see he got in there

Hans

[Agent Smith]

Originally Posted by 625

Please post feedback on that sight. I'm looking to get that exact one. Let us know how you like it! Thanks.

I'm very, very happy with it. It's a very high quality sight. The only drawback is the price, but if you don't mind spending $700 on it, then this sight is for you!

[soberbyker]

Tony & 27, thank you for the explanations, I do believe I understand now.

Information like you two have given me what what the rep system was meant for, if I hadn't given both of you rep recently, I surly would have for these answers, but the rep monster told me I had to spread it around before giving it to you two again.

Bill

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