A rather elementary question...dialing in for MOA

[Dan B]

I read a lot and post VERY little but I'm diving into the LR game and not seen this question asked...I could have just missed it buried in another thread. I'm playing with the ballistic program by Mr. King using a load for my Savage Striker 7mm-08 (Shilen 16.75" barrel) which shoots a 154gr SST at 2650fps. Through the last hunting season I used a modified zero to be capable of shooting to 400yds on deer...sighted the bottom duplex of a 3-12x32 Burris LER scope to zero at 300yds and had 14.4" of drop to 400yds. Did not shoot a deer at 400yds but did get one at 238 and another at 270yds...both one shot kills and hit exactly where aimed.

This year I am switching tactics to use dial ups...mainly to shoot a local 100/300/500yd groundhog target match but it will also translate to deer hunting. I do it currently with a Striker 22-250 and XP-100 .222 Rem...used this gun to dial in on a turkey at 229yds this fall. But I have shot these guns at all ranges to 500yds and my drop chart shows the exact clicks to each distance from a 100yd zero. The question...when the ballistic program says that from a 300yd zero (on the 7mm-08) I need to dial in 5.9 MOA to zero for 475yds (as an example)...how many clicks does this translate into when using a 1/8" click adjusment? A little math work tells me that I'd need to multiply the 5.9 MOA by the # of clicks per inch (8) which gives 47.2 then divide that by the range in relation to 100yd being 1...475yds would be 4.75. This yields approx 9.94 clicks?? Am I correct in this method or am I all wet?

This is a necessity for doping drop but adjusting for wind conditions is what got me really thinking on this.

TIA.......Dan B.

 

[Jon A]

All except the dividing part at the end--the ballistics program/drop chart should tell you the proper MOA at that range.

So, you were done at 47 clicks. I'm hoping your scope is marked in MOA--it could get easy to lose track of that many clicks pretty quickly. I prefer to "think" in MOA--5.25, 5.5, 5.75, 6.0, etc (for 1/4 min clicks) instead of trying to count the number of total clicks.

 

[littletoes]

THE MATH! IT HURTS! MAKE IT STOP!
Naw, just kidding. What I do is take the rifle/load out and try it. The balistic program is great to get close, but a known elevation is better, I think. For example, my 223 using 55 grain pills takes 28 clicks to be on at 600 yards, my 308 takes 15 clicks on my M3 to be on at that same yardage with 168's, 21 clicks for 750, ect. ect.
guess I'm just not a calculator or computer guy, I just take notes when I'm shooting.
Hope this helps, and good shooting! /ubbthreads/images/graemlins/wink.gif

 

[4ked Horn]

Math is for the mathematicians. Use this program http://biggameinfo.com/BalCalcAdv.aspx which can be found in the sticky post near the top of Bullets Barrels and Ballistics. It is posted by klinkers. In it you can enter the number of clicks per MOA on your scope (8) and you can recieve the clicks in raw clicks (hard to count) or in MOA plus additional clicks. This way you get directions from your 300 yard zero to your 475 yard zero that is simply 9+7 or 9 MOA and 7 clicks. I would however use a 100 yard base zero and then crank your knobs to all other ranges from there. This would show something like your 300 yd come ups as 11+2 MOA and your 475 yd come ups as 19+1.

Easy peasy lemon squeezy? (If I'm confusing you please ask for clarification. I get too wordy sometimes. I even confuse me. /ubbthreads/images/graemlins/tongue.gif)

You must enter all of the other pertinent data for your load and conditions but the format allows you to cut and paste the info directly into an excell spreadsheet for making printouts. It is a VERY flexible and user friendly program. Give it an honest evenings try. I'm sure it will help quite a bit.

 

[sscoyote]

U know i was about to make a comment on this to welcome u to the forum, and then i saw the B after the Dan part. Then i realized who it was. Welcome anymay Dan-- good to see u here.

After playing this long-range game, with the help of this forum, and several others, i would say one of the most important things i've learned is how to relate MOA to IPHY (inch per hundred yd.) to mil-dot math. MOA is definitely the most important concept IMO since that's the link between your reticle stadia, turret comeups, and ballistics programs, since most ballistic programs calculate drop in MOA. I always try to think of these concepts as the spokes of a gigantic wheel that defines these ANGULAR measurements.

Here's the conversions--

1 MOA= 1.05 IPHY
1 milliradian (mil-dot, dot to dot)= 3.6 IPHY or 3.4 MOA (3.6/1.05).

 

[Dan B]

Thanks fellas. I got to looking and the turrets on the 3-12x32 Burris LER scope (handgun scope) is marked in MOA. Once zeroed at 100yds I can loosen the cap, set it to zero then start practicing dialing using MOA per the charts.

I think I have the MOA thing figured out...but the mil-dot math? I'm working on it!! Any tips? I understand the concept...just need to be able to tie the terminology across the concepts.

 

[Guest]

[ QUOTE ]
So, you were done at 47 clicks. I'm hoping your scope is marked in MOA--it could get easy to lose track of that many clicks pretty quickly. I prefer to "think" in MOA--5.25, 5.5, 5.75, 6.0, etc (for 1/4 min clicks) instead of trying to count the number of total clicks.

[/ QUOTE ]

Better yet, use a NF with NP-R2 reticle, ( 2 MOA lines or 8 clicks ) go up 6 bars (48 clicks) and dial down only one click.

On my NF BR with 1/8 MOA, go up 6 bars and down two clicks.
By the time you count 47 (+/- a couple you mis-counted) I've dialed down one click, shot the elk, and started gutting.

 

[Jon A]

He said they were marked so he doesn't need to actually count them.

 

[davewilson]

i'm with little toes, take that puppy out, shoot it and see how many clicks it is to given ranges. this is the best.now factor in changes in temp, altitude, angle of the shot, and well, welcome to long range!

 

[curtis]

So it is better to start with a 100 yd zero as opposed to 200 yds? I guess this is a personal preference issue but I have been wondering if I should have my zero at 100 yds and just start practicing the MOA come-ups at various yards.

 

[Jon A]

The best thing about a 100 yd zero is altitude/conditions, etc have little effect on the ballistics. Yes, your rifle may have problems that change the 100 yd zero, but the bullet won't.

This means after you verify your zero at the new location/in the new conditions your corrected dope should be right on.

If you zero for 200, 300, etc, that's getting far enough that different altitudes will actually have a noticable effect on bullet drop. So your sea level zero isn't the same as your high altitude zero. You can get the gun on again at 300 or whatever and it'll be on there, but your dope will be changed for all other ranges.

In short, atmospheric conditions have such a tiny effect on the bullet's drop at 100 it can effectively be ignored. The farther the zero, the less true that becomes and the more error you build in. Of course there are programs (I believe Exbal is one) that can compensate for everything so you can zero wherever you want...but most programs don't have such capability--but it's hard for the beginner to tell that when he uses them.

BTW, just because you zero at 100 doesn't mean you have to walk around with zero MOA dialed into your scope. I know some worry about that, thinking it's a requirement of some sort. It's not, you can crank in 2-3 MOA on your scope after your zero to give you a nice 250-300 yd zero trajectory and it won't hurt anything at all. You'll just have fewer clicks to make if you get a nice long shot. /ubbthreads/images/graemlins/wink.gif

 

[curtis]

Thanks Jon,

Very informative and helpful. That is a good suggestion about having your rifle zeroed at 100 yds but dialing in for a 250 or 300 yd to walk around with. Thank you!

 

[4ked Horn]

[ QUOTE ]
So it is better to start with a 100 yd zero as opposed to 200 yds? I guess this is a personal preference issue but I have been wondering if I should have my zero at 100 yds and just start practicing the MOA come-ups at various yards.

[/ QUOTE ]

Having your elevation turret read 0 at 100 yards is elementary and practical. You don't have any confusion as to where your adjustments begin. You don't have to remember which rifle is zeroed for 100 yards and which is at 200 or which one has a 235 yard zero for a point blank range of 300 on elk.(If you don't know what a point blank range zero is let me know it is very handy.)

Like Jon said you don't have to walk around with your turrets set on zero at 100 yards. I preffer to though. When I stand up from a shooting position the scope goes right back to my 100 yard zero every time. When I go back to that gun 2 months later I don't wonder if it is set at my 100 yard zero or my 600 yard zero (one full turret rotation.)

Yes you should become very familiar with cranking your turrets for elevation and windage. You should use BOTH the ballistics chart to get you close and actual shooting of your gun at different ranges and taking notes of the exact number of MOA + remaining clicks to hit the center at your different distances. There is NO SUBSTITUTE FOR ACTUAL SHOOTING and there is no better way to get close quickly than a good drop chart.

Once you have found the correct adjustments for your gun and load in your climate and elevation the every yardage increment (200, 225, 250, 275 and so on) will have an "address" in MOA and additional clicks arround your turret. This is the quickest AND most repeatable way to assure a first round hit on your target.

As for learning the Milradian math that can come later. If you are using it right now to estimate range (while you are saving money for a good laser range finder /ubbthreads/images/graemlins/grin.gif) the formula is simple:

The targets size in yards X 1000. Divide that answer by the number of Mils it covers in your scope.

Lets say a coyote is 2 feet tall at the shoulder. He is 2/3 yards tall. 2/3 x 1000= 666. When you look at him through your scope he fills 2 Mils from foot to shoulder. 666 divided by 2 = 333. He is 333 yards away.

If you had time to do this math with a yote only 333 yards away then he has no idea you are there. Crank your elevation turret to your 325 yard address. check the wind an put clicks on for that.

Now dump him. /ubbthreads/images/graemlins/wink.gif

 

[bailey1474]

[ QUOTE ]
Having your elevation turret read 0 at 100 yards is elementary and practical. You don't have any confusion as to where your adjustments begin. You don't have to remember which rifle is zeroed for 100 yards and which is at 200 or which one has a 235 yard zero for a point blank range of 300 on elk.(If you don't know what a point blank range zero is let me know it is very handy.)

[/ QUOTE ]

I can attest to the confusion of any zero other than 100 yds. I thought I would be smart @ our last local shoot and just zero my rifles @ 250 yds. This would mean that I would have to do less cranking to get on target @ 250, 400 and 500 yds. I had a very frustrating day @ the longer ranges so I thought I would come to 100 yds and score a few hits. I turned my knob back to zero and shot. I missed!!!! After a few choice words I fired again, and missed AGAIN!!!! In the heat of the moment I had forgotten that my zero was 250 yds and aimed dead center of the 3" target.

Would I have missed a deer? No, but it is much easier and more precise (in my opinion) to set the zero @ 100 yds. All of my rifles are so darn heavy and long that there is no way I'm going to be able to get a quick walking shot off anyway.