Justification for 50 Yard Zero

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[ARCHIVED THREAD] - Justification for 50 Yard Zero

Posted: 10/24/2006 9:09:39 AM EDT

I'm currently in Iraq. Currently we zero our weapons at 25 meters. Who can point me to a ballistic table or program so that I can justify using a 50 yard zero?

I want to show them what the two different trajectories look like with the same weapon and ammo.

The weapon is an M4 carbine and the ammo is 62 gr green tip. The optic is a Compact ACOG 2x mounted on the carry handle.

Posted: 10/24/2006 9:45:42 AM EDT

[#1]

The primary reason for zeroing at 50 is to be within an inch or two from 50 to roughly 200 yrds. It requires modifications to carry handles and A2 sights to have the correct comeups at extended ranges. Is there a reason the 300m zero isn't working for you?

Posted: 10/24/2006 10:13:32 AM EDT

[#2]

Using an ACOG, you should keep with the accepted zeroing practice. But, part of that process is to Verify zero at the 100 yard line (and out to 300 if possible).

25 yards is a Battle Sight Zero. Which means, pretty close.

That said. I have zeroed at 1" high at 50 yards with an ACOG. This gives you a +- 3" point of impact out to 300 yards, using the main wire, and no hold off.

Posted: 10/24/2006 10:14:45 AM EDT

[#3]

Stoney,
Send me an e-mail and I can supply you with the drop tables and hi-res versions.

BTW if you have a Compact ACOG on top of the carry handle you change the equation a bit.

Zeroing as indicated) will raise the trajectories throughout the range. The 50y zero will still be usable, but the 25M zero get's really shitty in the mid range (say 150-250y). With Compact ACOGS on the carry handle 75yards is a better option for zeroing (it comes closer to replicating the 50y trajectory using sights that are 2.6" over the bore (like irons and Aimpoints).

Posted: 10/24/2006 10:16:34 AM EDT

[#4]

Ooops... forgot.

Try Point Blank software (free). It will get you in the ballpark.

Posted: 10/24/2006 10:23:09 AM EDT

[#5]

Ok Trajectory using 25M with a C-ACOG on top of the carry handle:


   Range Drop Drop Windage Windage Velocity Mach Energy Time Lead Lead 
   (yds) (in) (moa) (in) (moa) (ft/s) (none) (ft•lbs) (s) (in) (moa) 
0  -3.5 *** 0.0 *** 3033.4 2.717 1266.5 0.000 0.0 *** 
25 -0.2 -1.0 0.1 0.2 2953.2 2.645 1200.4 0.025 4.4 16.8 
50  2.8 5.3 0.2 0.5 2874.5 2.575 1137.3 0.051 8.9 17.1 
75  5.5 7.0 0.5 0.7 2797.1 2.505 1076.9 0.077 13.6 17.3 
100 8.0 7.6 1.0 0.9 2721.2 2.437 1019.2 0.104 18.4 17.6 
125 10.1 7.7 1.5 1.2 2646.5 2.370 964.1 0.132 23.3 17.8 
150 12.0 7.6 2.2 1.4 2573.1 2.305 911.3 0.161 28.4 18.1 
175 13.5 7.4 3.1 1.7 2500.9 2.240 860.9 0.191 33.6 18.3 
200 14.7 7.0 4.1 2.0 2429.8 2.176 812.7 0.221 38.9 18.6 
225 15.5 6.6 5.3 2.2 2359.9 2.114 766.6 0.252 44.4 18.9 
250 15.9 6.1 6.6 2.5 2291.1 2.052 722.5 0.285 50.1 19.1 
275 15.9 5.5 8.1 2.8 2223.4 1.991 680.5 0.318 56.0 19.4 
300 15.5 4.9 9.8 3.1 2156.8 1.932 640.3 0.352 62.0 19.7 
325 14.6 4.3 11.6 3.4 2091.4 1.873 602.0 0.387 68.2 20.0 
350 13.2 3.6 13.7 3.7 2027.1 1.816 565.6 0.424 74.6 20.4 
375 11.3 2.9 15.9 4.1 1964.0 1.759 530.9 0.461 81.2 20.7 
400 8.8 2.1 18.4 4.4 1902.1 1.704 498.0 0.500 88.1 21.0 
425 5.7 1.3 21.1 4.7 1841.5 1.649 466.8 0.540 95.1 21.4 
450 2.0 0.4 24.1 5.1 1782.2 1.596 437.2 0.582 102.4 21.7 
475 -2.4 -0.5 27.2 5.5 1724.3 1.544 409.2 0.625 109.9 22.1 
500 -7.6

Note you're running about 16" HIGH at 250-275 yards.

Here are the results from a 50y zero (which comes out to a 300y zero for your setup - not a bad zero)


   Range Drop Drop Windage Windage Velocity Mach Energy Time Lead Lead 
   (yds) (in) (moa) (in) (moa) (ft/s) (none) (ft•lbs) (s) (in) (moa) 
0   -3.5 *** 0.0 *** 3033.4 2.717 1266.5 0.000 0.0 *** 
25  -1.6 -6.2 0.1 0.2 2953.2 2.645 1200.4 0.025 4.4 16.8 
50  0.0 0.0 0.2 0.5 2874.5 2.575 1137.3 0.051 8.9 17.1 
75  1.4 1.7 0.5 0.7 2797.2 2.505 1076.9 0.077 13.6 17.3 
100 2.4 2.3 1.0 0.9 2721.2 2.437 1019.2 0.104 18.4 17.6 
125 3.2 2.5 1.5 1.2 2646.5 2.370 964.1 0.132 23.3 17.8 
150 3.7 2.4 2.2 1.4 2573.1 2.305 911.3 0.161 28.4 18.1 
175 3.9 2.1 3.1 1.7 2500.9 2.240 860.9 0.191 33.6 18.3 
200 3.7 1.8 4.1 2.0 2429.8 2.176 812.7 0.221 38.9 18.6 
225 3.1 1.3 5.3 2.2 2359.9 2.114 766.6 0.252 44.4 18.9 
250 2.2 0.8 6.6 2.5 2291.1 2.052 722.5 0.285 50.1 19.1 
275 0.8 0.3 8.1 2.8 2223.4 1.991 680.5 0.318 56.0 19.4 
300 -1.0 -0.3 9.8 3.1 2156.9 1.932 640.3 0.352 62.0 19.7 
325 -3.3 -1.0 11.6 3.4 2091.4 1.873 602.1 0.387 68.2 20.0 
350 -6.0 -1.7 13.7 3.7 2027.1 1.816 565.6 0.424 74.6 20.4 
375 -9.3 -2.4 15.9 4.1 1964.0 1.759 530.9 0.461 81.2 20.7 
400 -13.2 -3.2 18.4 4.4 1902.1 1.704 498.0 0.500 88.1 21.0 
425 -17.7 -4.0 21.1 4.7 1841.5 1.649 466.8 0.540 95.1 21.4 
450 -22.8 -4.8 24.1 5.1 1782.2 1.596 437.2 0.582 102.4 21.7 
475 -28.6 -5.7 27.2 5.5 1724.3 1.544 409.2 0.625 109.9 22.1 
500 -35.1 -6.7 30.7 5.9 1667.8 1.494 382.9 0.669 117.7 22.5

and now for 75y (which is near optimal for your optic setup IMHO):


   Range Drop Drop Windage Windage Velocity Mach Energy Time Lead Lead 
   (yds) (in) (moa) (in) (moa) (ft/s) (none) (ft•lbs) (s) (in) (moa) 
0  -3.5 *** 0.0 *** 3033.4 2.717 1266.5 0.000 0.0 *** 
25 -2.1 -7.9 0.1 0.2 2953.2 2.645 1200.4 0.025 4.4 16.8 
50 -0.9 -1.7 0.2 0.5 2874.5 2.575 1137.3 0.051 8.9 17.1 
75  0.0 0.0 0.5 0.7 2797.2 2.505 1076.9 0.077 13.6 17.3 
100 0.6 0.6 1.0 0.9 2721.2 2.437 1019.3 0.104 18.4 17.6 
125 1.0 0.7 1.5 1.2 2646.5 2.370 964.1 0.132 23.3 17.8 
150 1.0 0.6 2.2 1.4 2573.1 2.305 911.3 0.161 28.4 18.1 
175 0.7 0.4 3.1 1.7 2500.9 2.240 860.9 0.191 33.6 18.3 
200 0.0 0.0 4.1 2.0 2429.8 2.176 812.7 0.221 38.9 18.6 
225 -1.0 -0.4 5.3 2.2 2359.9 2.114 766.6 0.252 44.4 18.9 
250 -2.4 -0.9 6.6 2.5 2291.1 2.052 722.5 0.285 50.1 19.1 
275 -4.2 -1.5 8.1 2.8 2223.4 1.991 680.5 0.318 56.0 19.4 
300 -6.5 -2.1 9.8 3.1 2156.9 1.932 640.3 0.352 62.0 19.7 
325 -9.2 -2.7 11.6 3.4 2091.4 1.873 602.1 0.387 68.2 20.0 
350 -12.4 -3.4 13.7 3.7 2027.1 1.816 565.6 0.424 74.6 20.4 
375 -16.2 -4.1 15.9 4.1 1964.0 1.759 530.9 0.461 81.2 20.7 
400 -20.5 -4.9 18.4 4.4 1902.1 1.704 498.0 0.500 88.1 21.0 
425 -25.4 -5.7 21.1 4.7 1841.5 1.649 466.8 0.540 95.1 21.4 
450 -30.9 -6.6 24.1 5.1 1782.2 1.596 437.2 0.582 102.4 21.7 
475 -37.2 -7.5 27.2 5.5 1724.3 1.544 409.2 0.625 109.9 22.1 
500 -44.2 -8.4 30.7 5.9 1667.8 1.494 382.9 0.669 117.7 22.5

Posted: 10/24/2006 10:53:28 AM EDT

[#6]

Quoted:
groups.msn.com/isapi/fetch.dll?action=MyPhotos_GetPubPhoto&PhotoID=nJwAAAJ8LDLlTHuHu8*ZTaAdbXcSFufhhy6hEhz0LOkn4oCLrHkSP3xWE!dDnzgONgh8kZqX2k*Y

Stoney,
Send me an e-mail and I can supply you with the drop tables and hi-res versions.

BTW if you have a Compact ACOG on top of the carry handle you change the equation a bit.

Zeroing as indicated) will raise the trajectories throughout the range. The 50y zero will still be usable, but the 25M zero get's really shitty in the mid range (say 150-250y). With Compact ACOGS on the carry handle 75yards is a better option for zeroing (it comes closer to replicating the 50y trajectory using sights that are 2.6" over the bore (like irons and Aimpoints).

Thanks,

This is exactly what I'm looking for.
E-mail sent with my e-mail addy.

Posted: 10/24/2006 12:07:08 PM EDT

[#7]

As an Army guy who has qualified a few times and used the Army 25 meter zero method, my question is:

Can I use the 25 yard zero method with other types/weights of .223 in the AR 15 Carbine???

Thanks in advance.

Posted: 10/24/2006 12:16:40 PM EDT

[#8]

Quoted:
As an Army guy who has qualified a few times and used the Army 25 meter zero method, my question is:

Can I use the 25 yard zero method with other types/weights of .223 in the AR 15 Carbine???

Thanks in advance.

It depends. Technically, no, trajectories will not be exactly the same. Practically, yes, the differences in trajectory between 55 to 75 grain ammo out to 300 meters is still minute of man close.

Posted: 10/24/2006 12:22:38 PM EDT

[#9]

Quoted:
It depends. Technically, no, trajectories will not be exactly the same. Practically, yes, the differences in trajectory between 55 to 75 grain ammo out to 300 meters is still minute of man close.

I agree. It's not exact, but it's close enough for Govt Work.

Posted: 10/24/2006 12:24:53 PM EDT

[#10]

Guys...I like them answers. Thx.

Then I would verify at 100 yards.

Posted: 10/24/2006 12:59:05 PM EDT

[#11]

Forest,

How did you figure the sight over bore for the Compact ACOG on a carry handle? Is there some sort of table somewhere that list the optics and mount combos?

I'd like to figure out the trajectory for xm193 out of my 14.5" with EOTech on RRA Dominator back home.

Posted: 10/24/2006 1:10:20 PM EDT

[#12]

Quoted:
How did you figure the sight over bore for the Compact ACOG on a carry handle? Is there some sort of table somewhere that list the optics and mount combos?
.

I used to have a carbine with that setup. IIRC it was 1" over the standard HOB - which is what I used for the above tables.

Figure on 3.5" and you should be good to go. Of course if you want precise you can take out the calipers and measure the distance from the center of the peep sight to the center of the optic.

Posted: 10/24/2006 1:34:36 PM EDT

[#13]

Charts are nice and pretty, but unless you can "show" them something Its probably a lost cause.

I never gave the matter much thought until a few weeks ago at the class with Lynn.

My suppressed 11.5" is zeroed at 50yds (2733fps if it matters).

During the lunch break in the class I went over to the long (250yd) range which was still full of all the steel from the match the weekend before. Square, round and diamond, probably 10".

Anywho....

I snapped my 3x magnifier on and aimed just above the furthest plate. The bullet hit just above the plate. Next shot I put the dot in the middle of the plate and *CLANG*. Same dot that is dead on at 50yds was dead on at 250yds. I emptied the rest of the 28rd mag, on the various plates, holding center and I didnt miss again. A head sized target, took a hit each time. Not sure if they were center hits or not, but they were hits.

I'm a believer in the 50yd zero, and its ability out to 250.

You need to set up a reactive target at 50yds and 250yds and show them.

I'm heading back there in a few weeks for the "Super Dave" class, which is supposed to go beyond 250yds. I'll let you know how it goes.

Posted: 10/24/2006 1:50:50 PM EDT

[#14]

Big Bore makes an excellent point. Charts get them interested, but the proof is in the pudding so to speak.

Posted: 10/24/2006 2:03:49 PM EDT

[#15]

I know bigbore personally, so I always value his advice. The problem with demonstrating this is our range only goes to 100 yards. Don't laugh, the first time I was here, most ranges were only 25 meters. Okay for pistol and close rifle work, but not good for anything else.

Posted: 10/24/2006 2:18:28 PM EDT

[#16]

SImple demp then. Put up a target showing just the head sticking over a 'wall'. Try to shoot it 10 times with a 50y zero. Then try the same shot 10 times with a M4 zeroed the military way. They'll be surprised at how many miss or just graze the top of the head.

Posted: 10/28/2006 4:18:08 PM EDT

[#17]

Zero at 42 meters will give you a FLAT 250 meters. Works great for me.

Posted: 10/28/2006 7:57:18 PM EDT

[#18]

I zero at 25 meters with a Leupold 2.5-8 mildot and I hit within an inch of the eyeball on a Jane Fonda head target with M-193, M855, and HST 77 grain hpbt. Three distinct shot groups. If I want to make an eyeball shot I use the HST but the others get me to the head just fine.

Posted: 11/1/2006 2:51:30 PM EDT

[#19]

Bigbore have fun at super dave

one of my buddies will be there at it il lbe deep in the wood hunting and filming for the tv show.....

his name is MAtt