AR15.Com Archives
 AR-10 Zerp
lear35guy  [Member]
9/29/2011 1:20:33 PM
Hi Folks,

Brand new to the website and forum. Just picked up an AR-10A4 and am looking for zeroing information. I did a search, but didn't get any hits. If the mods have a thread stored and can point me to it that would be great.

I haven't picked up a rifle in 25 or so years since my M16A1. We didn't even have elevation on the rear sight back then. I've Googled and got the M61A2/A3 zero off the Army website, and also found the old M14 manual. But can't find anything definitive from Armalite or anywhere on zeroing procedures with bius.

I have to keep this "soldier" simple for me. I used to enjoy shooting back then, but I really picked up the weapon because I felt I needed to get something before i couldn't.

I plan on shooting for awhile with buis sights to really get to know this rifle, then I'll get a scope for it.

So, 25/250? 50/300? what are some of y'all using out there?

Thanks for he help!!
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lear35guy  [Member]
9/29/2011 1:21:21 PM
That should have been "Zero"
twotwo3  [Member]
9/29/2011 1:42:54 PM
You should get a double zero at 45 and 200 yrds. That's how mine is set.
crocodile427  [Member]
9/29/2011 2:02:03 PM
Also, check out TaylorWSO's FAQ thread at the top of this Forum. Has all the sighting info you need. Plus everything else. Its very in depth, informative, and thorough. Tons of great info in there.
lear35guy  [Member]
9/29/2011 2:31:26 PM
Thanks guys! I'm itching to get out to the range but I'm not going to waste bullets either.
TaylorWSO  [Life Member]
9/29/2011 5:49:05 PM

Originally Posted By lear35guy:
Thanks guys! I'm itching to get out to the range but I'm not going to waste bullets either.

well what are your intentions with the rifle, its really hard to waste ammo shooting 45yards at paper.

irons/red dot/scope/ paper/people/hunting/ looking cool,gp???

you use will dictate the sight in recommendations

read the faq


lear35guy  [Member]
9/30/2011 3:15:43 PM
Didn't want to waste bullets before I got a good zero.

Irons first out to 400y. I was good with the A1 out to that, so I'll get comfortable with that first, and feel that will force me to get to know this rifle. Scope after that. I've got a range available with measured distance out to 600y.

Goal is to be familiar/comfortable and be able to hit what I'm shooting at. Just in case I need to use it.

If you're a WSO, then you know the pilot mentality and need to look cool.
mike12345  [Member]
9/30/2011 5:47:59 PM
Originally Posted By twotwo3:
You should get a double zero at 45 and 200 yrds. That's how mine is set.


its 25 and 200.

depends on ammo but im running 175gr 2600FPS .495 BC

check a ballistics calculator to be sure. If you zero at 45, its 45 and 120. not so good. or 50 and 100
mike12345  [Member]
9/30/2011 6:20:38 PM
i just punched in .304BC 62gr at 2900FPS (M4 w M855/SS109)

thats zero'd at 25 & 235
50m puts it at 50 and 130

so 25m is still best guys.
crocodile427  [Member]
10/1/2011 1:24:10 PM
Originally Posted By mike12345:
i just punched in .304BC 62gr at 2900FPS (M4 w M855/SS109)

thats zero'd at 25 & 235
50m puts it at 50 and 130

so 25m is still best guys.


For 5.56 yes, but not for 308.
PaperStreet  [Team Member]
10/1/2011 1:56:13 PM
I use a MPBR zero. MPBR is Maximum Point Blank Range. Basically, a MPBR zeroed gun will be 3" high and 3" low out to the MPBR range for a large game target (deer, etc.).

Figure 2.75" high at 100 yds will get you close for most .308/7.62 rounds. That will put you 3" high at about 130 yds. and 3" low at about 270 yds. That will keep you in kill zone of large game without sight adjustments out to 270-300.

Research and decide if it is for you.

ETA: Please change your thread title. It is confusing and won't be picked up in searches for 'zero'. Thanks.


mike12345  [Member]
10/1/2011 6:05:43 PM
Originally Posted By crocodile427:
For 5.56 yes, but not for 308.


read my post above that.
mike12345  [Member]
10/1/2011 6:36:02 PM
OK I got your MPBR trajectory right here. This includes your + 2.75in zero, MPBR without the +2.75in zero puts 270yards at 0.0 so your zeroing at 270yards basicly.
(yd) (in) (ft/s)
10 -0.6 2587
20 0.3 2569.7
30 1.1 2551.6
40 1.9 2533.6
50 2.6 2515.7
60 3.2 2497.9
70 3.8 2480.1
80 4.4 2462.4
90 4.9 2444.7
100 5.3 2427.2
110 5.6 2409.7
120 6.0 2392.2
130 6.2 2374.9
140 6.4 2357.6
150 6.5 2340.4
160 6.6 2323.2
170 6.6 2306.2
180 6.5 2289.1
190 6.4 2272.2
200 6.2 2255.3
210 5.9 2238.5

220 5.5 2221.8
230 5.1 2205.1
240 4.6 2188.5
250 4.1 2172.0
260 3.5 2155.5
270 2.7 2139.1

The best is just to zero at 25

range, traj. velocity.
10 -0.9 2582
15 -0.6 2573
20 -0.3 2565
25 0.0 2556
30 0.3 2547
35 0.5 2538
40 0.7 2530
45 1.0 2521
50 1.2 2512
55 1.4 2504
60 1.5 2495
65 1.7 2486
70 1.9 2478
75 2.0 2469
80 2.1 2461
85 2.2 2452
90 2.3 2443
95 2.4 2435
100 2.5 2426
105 2.5 2418
110 2.5 2409
115 2.6 2401
120 2.6 2393
125 2.6 2384
130 2.5 2376
135 2.5 2367
140 2.4 2359
145 2.4 2351
150 2.3 2342
155 2.2 2334
160 2.0 2326
165 1.9 2318
170 1.8 2309
175 1.6 2301
180 1.4 2293
185 1.2 2285
190 1.0 2276
195 0.7 2268
200 0.5 2260
205 0.2 2252
210 -0.1 2244
215 -0.4 2236
220 -0.7 2228
225 -1.0 2220
230 -1.4 2212
235 -1.8 2204
240 -2.1 2196
245 -2.6 2188
250 -3.0 2180
255 -3.4 2172
260 -3.9 2164
265 -4.4 2156
270 -4.9 2148
mike12345  [Member]
10/2/2011 4:35:30 PM
I thought some more about what your doing, its not MPBR but just a zero at 2.75in high at 100

notice how this is a difference of .01 in at 25? you have to hit perfectly .1in high every time at 25 to see the 0.7 in difference at 270.

So Im still going to say just zero at 25,

5 -1.2 2590.9
10 -0.8 2581.8
15 -0.5 2572.7
20 -0.2 2563.7
25 0.1 2554.7
30 0.3 2545.6
35 0.6 2536.6
40 0.9 2527.7
45 1.1 2518.7
50 1.3 2509.8
55 1.5 2500.8
60 1.7 2491.9
65 1.9 2483.0
70 2.1 2474.2
75 2.2 2465.3
80 2.3 2456.5
85 2.5 2447.7
90 2.6 2438.9
95 2.7 2430.1
100 2.7 2421.3
105 2.8 2412.6
110 2.9 2403.9
115 2.9 2395.1
120 2.9 2386.4
125 2.9 2377.8
130 2.9 2369.1
135 2.9 2360.5
140 2.8 2351.9
145 2.8 2343.2
150 2.7 2334.7
155 2.6 2326.1
160 2.5 2317.5
165 2.4 2309.0
170 2.2 2300.5
175 2.1 2292.0
180 1.9 2283.5
185 1.7 2275.0
190 1.5 2266.6
195 1.3 2258.1
200 1.1 2249.7
205 0.8 2241.3
210 0.5 2232.9
215 0.2 2224.6
220 -0.1 2216.2
225 -0.4 2207.9
230 -0.7 2199.6
235 -1.1 2191.3
240 -1.5 2183.0
245 -1.9 2174.8
250 -2.3 2166.5
255 -2.7 2158.3
260 -3.2 2150.1
265 -3.7 2141.9
270 -4.2 2133.7
GunnyG  [Team Member]
10/2/2011 4:40:52 PM

Originally Posted By lear35guy:
That should have been "Zero"

I'm pretty sure that "zerp" is etymologically related to both "herp" and "derp".

OP: Enjoy your rifle! I've got a 16" AR-10A4 carbine, and really like it..
crocodile427  [Member]
10/3/2011 3:29:52 PM
Originally Posted By mike12345:
Originally Posted By crocodile427:
For 5.56 yes, but not for 308.


read my post above that.


Point taken, Im going to re-zero this weekend. At 25yds.
panzer  [Team Member]
10/10/2011 4:44:50 AM
Mike, what sight height are you using in your calculations? With a 175 Sierra @2570 fps a 50 yd zero equals a 200 yd zero. That's with an AR10 sight height of 2.7 inches above the bore centerline. An AR15 standard sight height is 2.6 in, and with m855 from an actual M4, with M855 @ 2900 fps, a 50 yd zero is within an inch of a 200 yd zero. So your numbers aren't correlating with my numbers or my experiences with 50 yd zeros and actual 200 yd confirmations. Im just a little perplexed at your numbers, I shoot AR15's and AR10's and M14's competitively and the 50 yd zero will get you within 1/2 minute of 200 yd zero with just about any service rifle load. Sight height over bore centerline is critical to accurate calculations for actual zero of any rifle. Of your just calculating based on BC and speed, your showing only the bullets path, not a true representation of the bullets flight path in relation to the line of sight. Just a thought to why the numbers are so different.


ETA... Actually thinking about it and going back and changing my sight height to 0, I get your numbers, so I have to say your inputs aren't accurate and your data is therefore askew. Try inputting 2.6 inches as a sight height and see what your numbers are. That's standard AR height. Also very critical to get accurate output.
mike12345  [Member]
10/14/2011 7:42:43 AM
I did a hight of 1.5 2600 muzzle

im using a 1.45 rings so im actually at 2.768
panzer  [Team Member]
10/14/2011 11:31:19 PM
plug 2.768, or 2.8 in your program and I bet your numbers get alot more accurate.
panzer  [Team Member]
10/17/2011 1:18:23 AM

Using your sight height and bullet and velocity, here are the correct drop values.. many people in the Army are pushing right now to change the zero from 25 meters to 50 yds because it is a much more versatile zero. as you can see the POI is much closer to POA for a longer range than the 25 yd zero.

50 YD zero 25 yd Zero
yds Path yds Path

25 -1.2 25 0.0
50 0.0 50 2.4
75 0.9 75 4.5
100 1.4 100 6.3
125 1.5 125 7.6
150 1.3 150 8.6
175 0.7 175 9.2
200 -0.4 200 9.4
225 -1.8 225 9.1
250 -3.7 250 8.4
275 -6.1 275 7.3
300 -8.9 300 5.7
325 -12.3 325 3.5
350 -16.1 350 0.9
375 -20.5 375 -2.2
400 -25.4 400 -5.9

now, take the standard AR10 Sight Height of 2.7, typical of iron sights, using the same load 175 sierra @2600 and you get the following data.


50 YD zero 25 yd Zero
yds Path yds Path
25 -1.2 25 0.0
50 0.0 50 2.4
75 0.8 75 4.4
100 1.3 100 6.1
125 1.4 125 7.4
150 1.2 150 8.3
175 0.5 175 8.8
200 -0.6 200 8.9
225 -2.1 225 8.6
250 -4.0 250 7.8
275 -6.4 275 6.6
300 -9.3 300 4.9
325 -12.7 325 2.7
350 -16.5 350 0.0
375 -20.9 375 -3.2
400 -25.9 400 -7.0


and for more info on the regular old AR in 5.56, take alook at these handy threads.

Improved battle sight Zero

Real good graph showing the paths!

Another good one for 75 gr match


So moral of the story, Use the correct inputs so you get the correct outputs. And That I still believe a 50/200 yd zero is a better choice for anything within 300 yds. 5.56,308 55-175 gr.

So you guys still going to go rezero to 25 yds now?
crocodile427  [Member]
10/18/2011 10:21:09 AM
I tried over the weekend. But, it may have been me, I seemed to do much worse when I went for 25yd. I dont have a rest or anything, so I just use the range's sand bags and prop they have there. So I think I need to get a bench rest to do this right. I thought I could manage, but obviously not.

I do appreciate all the data though. Is this some program you are using? Or do you have the formulas and all the jive? I have seen the KAC Bullet Drop app for the smart phones, but have seen nothing else beyond using pencil and paper.
panzer  [Team Member]
10/18/2011 2:37:49 PM
i have 2 programs on the phone, Bullet flight is one, and JBM Field Ballistic is the other, also you can go on google and just type, " Ballistic calculator" and there are a few out there that are free. just make sure you have all your inputs correct and they are all pretty accurate. bullet flight for me has been within a 1/2 MOA or better with every rifle I have used it for. (7 or so) and will take readings from local weather and compensate as well from your zero days conditions. Only really a big deal with precision rifles, with Irons Its a factor, but not much of one as the targets are usually bigger.
Scaup58  [Team Member]
10/19/2011 6:37:11 PM
Hornady has a free one on their web site.
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