What distance to sight-in?

[Lawdog-1]

Soon, I will go to qualify with my Colt LE 6920 and a Eotech 512 in a LaRue mount or Aimpoint M2 in a LaRue mount or a Aimpoint ML3 2.0 MOA in a LaRue mount, not sure which one to use. I think, I will like Eotech the best. I will be shooting at 25 yards + 50 yards and 100 yards. I have my Aimpoint ML3 2.0 MOA sighted-in at 50 yards. Is sighted-in at 50 yards the right distance to qualify or do I need to sight-in at 100 yards?

[Robb Jensen]

The best zero is for POA/POI at 50yds.

[rob_s]

When I took a Randy Cain carbine class earlier this year, we zeroed at 50, moved out to 200 and confirmed zero (and fine tuned if necessary), and then moved back in to 50 to reconfirm.

Absent the ability or facilities to go through the above, a 50 yard zero should more than suffice.

[MX5]

I'm partial to 50 yd. zero.

[Mojo58]

One of my instructors insisted on a 50 yard zero. Mine's zeroed for 50 yards.

[KevinB]

Weapon, ammo, optic and role will best determine your optimal zero.


Lawdog
GotM4 has correctedly mentioned that for 99% of people using irons and a CCO that the Improved Battle Sight Zero of 50yds (or 50m if your that way) is optimal.

Key is knowning you trajectory and what you want to do with the system.

I had someone argue that for my 16" Recce with Short Dot I should be 50m zero'ing - nothing is an absolute, and if someone gives absolutes - start to wonder.

As for which optic -- which one do you prefer and shoot best with?

[paulosantos]

Lawdog, My two favorite zero's are actually the 50 yard and 100 yard zero.

The 50 yard zero is great since it is the flattest from 0-250 yards. The problem with the 50 yard zero is that you will have holdovers and holdunders, depending on the range:

With a 50 yard zero here are the trajectories with M193 as an example:
25 yards: -1.2" low.
50 yards: 0".
75 yards: 0.9" high.
100 yards: 1.6" high.
150 yards: 2.0" high.
200 yards: 1.1" high.
250 yards: -1.4" low.

With a 100 yard zero here are the trajectories:
25 yards: -1.6" low.
50 yards: -0.8" low.
75 yards: -0.3" low.
100 yards: 0".
150 yards: -0.4" low.
200 yards: -2.1" low.

As you can see, with the 100 yard zero everything will be a holdover so it is easy to remember and not get confused. But it is really up to you and what you feel comfortable shooting. We have to qualify 4 times a year at work with carbines and I feel comfortable with both, but I choose the 100 yard zero. I also feel more comfortable with an Aimpoint, but we are issued EOTechs and they are also very good. Hope it helps.

[Lawdog-1]

Well, My PD. is very very small so if I want to carry a M4GERY in my patrolcar, I will have to use my own LE M4 and my own ammo. I plan on using Winchester white box 55 gr. Full metal Jacket ammo to carry in my Colt LE 6920.

[KevinB]

I'm honestly not too keen on your ammo selection.

[Lawdog-1]

KevenB, what type ,brand would you use if you had to supply your own ammo?

[rob_s]

Are there no limits to what you are "allowed" to carry?

[Lawdog-1]

Rob s, you are taling about ammo right, It has to be 55 gr. FMG.

[markm]

If it has to be 55gr FMJ, I'd go with an M193 load.

Q3131a (Win M193 made in Israel) would be optimal. I'd avoid Q3131 as the last pair of retail boxes I bought were pretty Nasty... Mixed head stamps, and skanky looking.

XM193 from Federal is another decent choice.

[Lawdog-1]

I forgot to that I can't use the steel core FMJ, it has to be the lead core FMJ.

[markm]

I forgot to that I can't use the steel core FMJ, it has to be the lead core FMJ.

I've never heard of any steel core 55gr FMJ anyway.

[R Moran]

I like the 50mtr zero, we use it at work, your within 2 inches of your POA according to Pauls chart, mopst people aren't going to be able to shoot that good on the 2 way range.

Hell, in a recent Vickers class, he basically said most people wont remember the offset for closer ranges anyway.

Ammo, I've had alot of trouble with Q3131/a, we also had some bad stuff at work.

Federal used ot have some 55grn FMJ in the Tactical line, not sure if they still do. I would look at American Eagle, or see if Black Hills/ Hornady makes a "duty quality" 55grn FMJ. Sealed case, primer, cannelure to keep the bullet in place and I believe it helps fragmentation.

Bob

[jackinfl]

Paul,
Can you run and post the same DATA for 25 yard POA/POI? Thanks

[paulosantos]

With a 25 yard zero here are the trajectories:
25 yards: 0".
50 yards: 2.4" high.
75 yards: 4.5" high.
100 yards: 6.3" high.
150 yards: 9.1" high.
200 yards: 10.5" high.
250 yards: 10.4" high.
300 yards: 8.5" high.
350 yards: 4.4" high.
400 yards: -2.1" low.

Here is the program for anyone interested:

http://www.eskimo.com/~jbm/calculations/traj/traj.html

[f.2]

5.56 mm duty loads (http://www.tacticalforums.com/cgi-bin/tacticalubb/ultimatebb.cgi?ubb=get_topic;f=78;t=001244), Tactical Forums, member DocGKR