M-4 50m zero vs. 25m zero
 

This is important. using M885 standard green tip 62gn. ammo in an M-4, the difference in zeroing the rifle at 50m instead of 25m means you can hold center mass out to almost 300m and still expect a hit in the vital area.

Here is the ballistics (bullet path in inches):

Z @ 50m: 25m -1.3", 50m 0.0", 100m +1.7", 150m +1.8", 200m +.2", 250m -3.4"

Z @ 25m: 25m 0.0", 50m +2.7", 100m +7.2", 150m +10.1" 200m +11.3", 250m +10.4"

After retiring in 00' from an ODA, I worked as a Dept. of Energy Firearms instructor for 4 years. When someone explained this to me I wished I had known this when I was on the team. It makes sense. Maybe it will help someone out.

I'm not an expert on this but have read in 2 or 3 sources that a 50m zero will also zero at 200.....your info at 250 makes sense but 200 does not....unless it is the grain or twist rate....my data was for 55gr with a 1:9
ss

Check it out with a ballistics program if you want to. I shot it on a range with both zeros and it's the real deal.

50 M Zero
 

I use the 50 M zero on my work amd personal guns. I have found it to be much better than the 25m or standard military zero for shooting from 25-200 meters.
Check out this web site. .

http://groups.msn.com/TheMarylandAR1...ngmethods.msnw

It has some graphs which show the fight path of the rounds using different zero methods.

If you guys come up with anything different than what they show please let me know so I can make adjustments.

Thanks!

SERPENT5XX

Most excellent thread!

When my agency started a patrol rifle program, we quickly learned that the 25m zero we were familiar with from the military was not a great plan. We went to the 50m zero for quite a while and found it to be much better. When talking torso shots to 300 it should work great.

Not meaning to hijack the thread, but we have since gone to a 100 yd zero. We looked at this after attending a school with Paul Howe. The premise is that the round is low everywhere except 100. It will be low up close regardless of zero due to sight offset and it's just easier for me to remember that it is always low rather than sometimes low and sometimes high. The listed data is my 16" carbine with 75gr Hornady TAP, but it should close with 62gr and 14.5"barrel.

15 yds -2.5" 50yd -1.5" 75yd -.75" 100yd -0 150yd -1.5" 200yd -3.5"

This works great with an optic like an Aimpoint or EOTech. I always remember to hold high in close and high way out there. Between 50 and 150 just aim dead on even if a head shot is all that's available. At longer ranges it is actually easier for me to hold the dot over the small targets than it is to cover up the target with the dot. This eliminates fooling with the brightness setting when bullets are flying. It also works okay with the ACOGs. When using iron you probably need to adjust the rear sight for range because it's hard to hit a small head and/or upper torso with that big front sight covering it up. If I am anticipating longer shots I might run the rear sight up a few clicks.

I have found both 50 and 100 zeros to be much superior to the 25m/300m one. I don't shoot out that far very often, and if I am then I don't mind adjusting to hit them out there. It's easier for me to think about shooting at a target out there than it is to adjust aim 7" at 100 yds with the 25m zero when I'm excited.

I haven't been on the Maryland AR15 site in a few years, but found it very informative reference the 50 m zero and other battle site zeroing techniques.

Take care
Allen

edit for: malfunction on the data entry due to computer illiteracy.

Good gouge agzant, Anybody seen the average engagement distance for Iraq say, among PMCs? I know, I know, it varies greatly.

I will try both 50 and 100 next week. Thanks for the tips fellows.

NDD,

Any info you can share with us on the 50 M vs. 100 M zero?

Do these figures work for a 10.5" barreled M4 as well?

With a muzzle velocity as much as 200 fps less, I think not, unless you can repeal the laws of physics.

TR

I had it zeroed at 100 for quite a while. I changed it back to 25 to test a new target. Works fine, but I suggest you shoot at whatever distances you need to and actually check where you are impacting.

I wasn't particularly attracted to the idea of a 50M zero.

Roger. Thank you.

Does anyone have the figures for a 10.5" barrel M4 handy?

Thanks, NDD.

At the risk of thinking too far outside the box, I have been experimenting with a 25m. zero on my red dot sights (EOTech 552 and 553), and a 100m. zero on my iron sights (Troy), which I usually leave in the up position anyway.

As long as you remember to transition for the long shots, which I am trying to train into, it should not be a problem.

At a closer range snap encounter, you are going to shoot the red dot anyway, and at the longer ranges, you are taking the time to aim more carefully.

Just an experiement, not advocating this for everyone.

TR

TR,
I have done that as well and really like it.