Advanced Marksmanship How do you flesh-out your DOPE from the few known ranges you have?

[punkwood2k]

I'm sure this has been asked a few times, but I honestly searched and couldnt find an answer in the forums.. Sorry.. :-(

How do you flesh out your DOPE card, from the few known ranges you have? For example.. I shoot at CRC like a lot of you, but the high power range does not have berms for 400 or 700 yards. The silhouette range has 200-500 meters, so that helps, but results in odd yardage (219, 547, ect) which are hard to formulate into a DOPE card. To complicate matters, I rarely have a partner, so I target a staked tennis ball and 10" hoop on the berm, which adds 40 yards.. Results are that I have Dopes for 200, 219, 328, 421, 547, 640, 840, 940, & 1040 yards.. How the heck do you create a 50 yard increment DOPE card and fill in the missing yardage?

related to that, is what is a good PC or Android ballistics calculator (preferably free or close), that might do that work for me? Makes it rough when Hornady's BC for my 178 A-Max is kinda optimistic, and I'm tired of guess & check trying to get their drop to match mine.

 

[djskit]

Just plug in your bullet and estimated speed to JBM (and other pertinent variables like scope height and zero distance) and compare the output to your dope. Tweak the speed until you get as close as possible to your results and then just run with all the other distances.

JBM is free!!!! Freeeeeee!!!!!!!!

JBM - Calculations - Trajectory (Simplified)

 

[punkwood2k]

yeah, I tried JBM and Hornady online ballistic calculators.. I can get one yardage or two to be close, but the rest are increasingly farther off. I'm looking for some kind of calculator that allows you to input the dope you know, and calculate the MOA values for the remainder.. I've tried tweaking my speed to match the curves as much as possible, but thats telling me my Chrony is 300 or 400fps minimum off the mark.. No way am I lobbing a 178gr 1000 yards, with only 2300 fps MV.

How do the Military or Police do it? They need one shot cold bore DOPE values, so their cards have to be spot on.. Do they go out and shoot groups every 10 yards? Kinda doubt it..

 

[doctordoctor]

Great question. I'm looking forward to the answer.

Sent from my SCH-I545 using Tapatalk

 

[CoryT]

Just plot the curve, you have plenty of data points. The fact that they are not 'even' ranges is meaningless. Insisting on dope cards that read every 50, or 25 or whatever is just trying to be 'neat and orderly'. Lets face it, real world, your UKD target is not likely to be on some even number anyway, so some degree of interpolation will always be required.

Now, because many ranges are marked in even 100's of yards, people shoot these ranges, then split the difference to get the 50 yard increments, then split it again to get 25's. When I do a class, I have students shoot every 100 out to 600, then every 50 out to 1K, it's nice to log the data if you can. Still, you range a target at 932 and what do you dial on? If you have 950 and 900, split the difference and add the odd amount if any, plenty close enough.

You have plenty of data points to plot a smooth decreasing radius curve on a graph with MOA or Mils on one leg and range on the other. Then make your chart in any increments you choose. I sometimes freak the class out with a chart that looks just like yours. Lets say you are at 11.75 MOA up at 547 and 16 MOA up at 640. 593 is dead between those, so 14 MOA up should work just fine, the math says 13.875, just round up to what you can actually dial on. It's really just that simple.

I've never understood the fascination with 'even number increments'. You need to know the curve, not any particular arbitrary points on it. Would a card with dope for every 31 yards be any less usable than a card with every 25 or 50? It would work just fine, if you in fact understand what you are doing.

 

[CoryT]

Also note that public ranges often have incorrect ranges listed anyway, add that to the environmental effects changing the POI on any given day, your ability to hold, the precision with which you actually mark your group, etc., all enter into it as well. Just because you have a range marked 600 yards does not mean it's not 605 or 593, and the weather on one day compared to another is going to change the POI by more than that range error, even assuming we had a perfect hold and knew the velocity of the next shot, which we don't.

 

[djskit]

yeah, I tried JBM and Hornady online ballistic calculators.. I can get one yardage or two to be close, but the rest are increasingly farther off. I'm looking for some kind of calculator that allows you to input the dope you know, and calculate the MOA values for the remainder.. I've tried tweaking my speed to match the curves as much as possible, but thats telling me my Chrony is 300 or 400fps minimum off the mark.. No way am I lobbing a 178gr 1000 yards, with only 2300 fps MV.

How do the Military or Police do it? They need one shot cold bore DOPE values, so their cards have to be spot on.. Do they go out and shoot groups every 10 yards? Kinda doubt it..

So, are you saying that by tweaking the speed, you get the right results but discount them because the speed appears to be wrong?

I've set-up at least a dozen rifles in this manner and generally get to within one or 2 clicks of the right answer. This is pretty straight forward stuff once you have the experience.

Several programs will allow you to put in real world dope at various distances and then it will extrapolate the full curve. Don't take this the wrong way, but my guess is you are "doing it wrong".

My 178 Amax's are going around 2725 and my 1000 yard dope is generally around 10.1 mils depending on the conditions. That's 34 MOA. This is based on a 100 yard zero. I just tweaked the output of my program and I see my 1040 yard dope would be 36.5 MOA

What's your 1040 dope?

 

[djskit]

 

[djskit]

I was able to get JBM to agree with a little tweaking. It doesn't do DA, but I think I backed into it.

 

[punkwood2k]

So, are you saying that by tweaking the speed, you get the right results but discount them because the speed appears to be wrong?

I've set-up at least a dozen rifles in this manner and generally get to within one or 2 clicks of the right answer. This is pretty straight forward stuff once you have the experience.

Several programs will allow you to put in real world dope at various distances and then it will extrapolate the full curve. Don't take this the wrong way, but my guess is you are "doing it wrong".

My 178 Amax's are going around 2725 and my 1000 yard dope is generally around 10.1 mils depending on the conditions. That's 34 MOA. This is based on a 100 yard zero. I just tweaked the output of my program and I see my 1040 yard dope would be 36.5 MOA

What's your 1040 dope?

My 178 AMax runs about 2727, very close to yours.. My 1040 dope is 34.75MOA with a 100yd zero as well..

And when I adjust my velocity to get close to my dope values, I can recreate the general curve / drop of my actual data, but only at much lower velocities.. It may just be inexperience, for sure.. but my results are pretty consistent when shooting, and consistently wrong when trying to use my ballistics calculator.. You mention several programs that allow you to input known dope, and interpolate backwards? Any specific programs that I can look at?

one more variable that I'm sure is skewing my results, is that my zero and MV was figured at 70degrees.. The day I ran through the High Power range, it was showing 100degrees in the unshaded shooting lines.. I didnt Chrono my loads that day, and I dont know the temperature sensitivity of IMR-4064, but I hear its pretty temperature stable.. ?

 

[fw707]

Check the "truing" feature in Strelok.
That might be what you're looking for.

 

[djskit]

We need to recognize the distinction between:

1) getting the correct dope across all ranges for similar conditions either at the same session or a later one, and

2) calculating correct dope as conditions change.

Calculating correct dope as conditions change is the next step in learning this, but unless you can nail your dope in similar conditions, venturing in the that step would be counter-productive, in my opinion.

 

[punkwood2k]

Check the "truing" feature in Strelok.
That might be what you're looking for.

I've been using Strelok primarily, but the recent update for it removed the "truing" feature.. :-(

 

[djskit]

My 178 AMax runs about 2727, very close to yours.. My 1040 dope is 34.75MOA with a 100yd zero as well..

And when I adjust my velocity to get close to my dope values, I can recreate the general curve / drop of my actual data, but only at much lower velocities.. It may just be inexperience, for sure.. but my results are pretty consistent when shooting, and consistently wrong when trying to use my ballistics calculator.. You mention several programs that allow you to input known dope, and interpolate backwards? Any specific programs that I can look at?

one more variable that I'm sure is skewing my results, is that my zero and MV was figured at 70degrees.. The day I ran through the High Power range, it was showing 100degrees in the unshaded shooting lines.. I didnt Chrono my loads that day, and I dont know the temperature sensitivity of IMR-4064, but I hear its pretty temperature stable.. ?

So what you're saying is my calculations, using 2 different programs, using your bullet and known speed correcly replicates your confirmed data, however, you are unable to replicate these results with your program?

 

[CoryT]

You don't need to use any software at all, a sheet of graph paper will work fine. Use the horizontal as range, space that out to fit 1050 yards. Use the vertical as MOA with 0 at the top and 35 MOA on the range line. Mark your data points on the page and draw in a smooth curve and you are all set. You can refine the curve as you add more data points.

No chronograph, no BC, no computer required. I don't even need to know the caliber, bullet weight, or exact elevation increments on the dial, just MOA or Mils.

If you zero at 100 yards, the temp change will not have any effect on your zero setting, but it may have some effect on your elevation setting for longer ranges. The only way to know what that effect is is to shoot under various conditions and note the change. I would note the conditions next to the data point on the graph. Once enough data is collected, you'll see how temp/elevation alter the curve and you can adjust as required.

 

[punkwood2k]

So what you're saying is my calculations, using 2 different programs, using your bullet and known speed correcly replicates your confirmed data, however, you are unable to replicate these results with your program?

It replicates my data at 1040 only.. thats not the problem, as I can get my calculators to match up on a single range as well.. its the REST of the curve that doesnt match up.. What the calculator gives me, and my confirmed dope only intersect at one point.. I can make that intersection any range I like by adjusting MV or BC, but I cant find values that will duplicate the ENTIRE curve, or even come close to it.. What I am finding is that the general curve of my bullet drop increases faster than the calculators I've used.. without graphing software, its obviously more difficult to explain.. but what I am seeing is that at longer ranges, my bullet drops faster than what Hornady, JBM, or Strelok say it should..

Guessing that I'm just going to quit stressing about it,and use the graph paper and ruler method to interpolate my other comeups... lol. Arts and crafts time!

 

[djskit]

It replicates my data at 1040 only.. thats not the problem, as I can get my calculators to match up on a single range as well.. its the REST of the curve that doesnt match up.. What the calculator gives me, and my confirmed dope only intersect at one point.. I can make that intersection any range I like by adjusting MV or BC, but I cant find values that will duplicate the ENTIRE curve, or even come close to it.. What I am finding is that the general curve of my bullet drop increases faster than the calculators I've used.. without graphing software, its obviously more difficult to explain.. but what I am seeing is that at longer ranges, my bullet drops faster than what Hornady, JBM, or Strelok say it should..
Guessing that I'm just going to quit stressing about it,and use the graph paper and ruler method to interpolate my other comeups... lol. Arts and crafts time!

Hit me with some data points and lets see how it tracks with what I can come up with.

 

[Trochlea]

Alternate solution, they recently approved steel targets at the 1000 yard range. They have firing lines at every 100 yards which would give you a more consistent firing distance. If you don't have steel, I have a 14 inch square with a portable set up live pretty close to you. Pm me if you need/want to either hit up the range or just borrow it.

 

[punkwood2k]

Alternate solution, they recently approved steel targets at the 1000 yard range. They have firing lines at every 100 yards which would give you a more consistent firing distance. If you don't have steel, I have a 14 inch square with a portable set up live pretty close to you. Pm me if you need/want to either hit up the range or just borrow it.

yeah, actually the steel was my intention, but its not up yet, so I had to use a tennis ball..

 

[Trochlea]

I saw someone had one of those stuck in the ground via a tent stake a couple weeks back. We can still set up personal steel, so if you want something bigger than a tennis ball, let me know.

 

[punkwood2k]

Hit me with some data points and lets see how it tracks with what I can come up with.

178gr Amax @ 2727fps & .495 BC
5225 altitude (I think)
100 degrees F

540 yards - 10.75 MOA
640 - 13.5 MOA
840 - 22.5 MOA
940 - 28 MOA
1000 - 31.6 MOA
1040 - 34.75 MOA

*some of these are slightly off, due to shooting at different elevation angles (some were raised berms, some were in the dirt) but should be pretty close to level values.*

 

[punkwood2k]

haha, I saw the same guy a few weeks ago on the silhouette range.. thats where I got the idea.

 

[SAPenguin]

Punkwood - apart from changing the velocity in your computer, you should also be able to change the B.C. as well. There should be a combo of velocity and BC that matches your actual dope very closely.

 

[djskit]

I was able to get close, but just don't have the tools to post it right now.

You are at over 5,000 feet and over 100 degrees. These are fairly extreme conditions. When you run your program, be sure to get that data in ther as well as the baro. A lot of programs default to "standard conditions" which just so happens to be much like the area I shoot.

Keep gathering data - good hard data at known distance on paper is preferable. Berms and steel, less so.

 

[djskit]

here it is...not looking too sharp.

 

[Geno C.]

Are all these shot on he same day under the same conditions? Actual pressure and humidity numbers could possibly get you closer yet.

 

[TacticalBoltKnob]

You need accurate velocity for your load and you need accurate environmental readings at YOUR shooting position, not a weather station 40 miles away with readings from an hour ago.

If you have these two things, your dope chart should be accurate every time. If you don't have these two things, you will probably blame the chart for being wrong, when it's not.

Garbage in, garbage out.

 

[djskit]

I'm guessing that his hit data may be from different days or not on paper (was it a basketball hoop and a tennis ball?) and like you said, a weather station 40 miles away.

If one can get solid data and several ranges (let's say, 500, 800 and 1,000) on paper and accurate atmospherics, it's pretty straigtfoward of filling in a data card via a ballistics ap or program.

We run intro to LR shooting clinics and have had 50 guys on the line - some have never shot past 300 yards and we have had all get good hits to 800 yards, many out to 1000.

My guy had a Kimber hunting rifle in 308 with a 22 inch barrel with 150gr Game Kings and a Vortex MOA hunting scope. He had a solid 100 yard zero and by the time we were at 500, we had correct elevation on the first round at 600 and 800. The wheels fell off at 900 as his bullets were tumbling.

 

[proneshooter]

Punkwood - apart from changing the velocity in your computer, you should also be able to change the B.C. as well. There should be a combo of velocity and BC that matches your actual dope very closely.

This.

 

[proneshooter]

My guy had a Kimber hunting rifle in 308 with a 22 inch barrel with 150gr Game Kings and a Vortex MOA hunting scope. He had a solid 100 yard zero and by the time we were at 500, we had correct elevation on the first round at 600 and 800. The wheels fell off at 900 as his bullets were tumbling.

Amazing what you can do with an accurate, light weight deer rifle, good dope, and solid fundamentals. Most fudds could not get first rounds hits on anything with that gun at more than 250 yards.

 

[Jaeger308]

As already posted change MV and BC numbers to slide your real world data into what a program calculates. Limit how much you change these variables however big changes create other problems in programs. Another thing to consider is calibration of your scopes travel, either go test it and put travel error into a percentage to multiply your solution or in a program change turret profiles of how much one value is...example: change 0.1 mil to 0.11 as see how that moves your numbers.

 

[flounderv2]

Check the following
Atmospheric conditions at zero and current (Letting ammo sit in the sun on a hot day could affect your drops)
Barrel Length, Twist
Site Height will give you some interesting difference if incorrect.
Scope Click Truing. There a chance your scope isnt tracking perfectly so your 1mil adjustment you dial may only be .85 or 1.1 if you know what I mean. This will cause more discrepancies at distance
What powder are you running. i.e Temp stability per deg T change.
Wind direction. Wind direction in the ballistics program will effect your drop at distance. So if you put in 10mph at 90deg but the wind was really 10mph coming from 11oclock, it will calculate different drops due to the winds affect on the bullet.

 

[rickp]

Last year I attended some training and a competition out at K&M Precision. All the targets we shot the whole time we were there were from 100y to just short or 1000. What made it interesting was that a lot of the targets the staff had us engage were set up at ranges like 312y, 536y 788y etc.. etc... (I;m using arbitrary numbers not actual ranges) the point is none of the actual ranges were at the typical exact ranges most people shoot, like 600y or 750y or 900y. Every target we had to engage took some interpolation on the part of the shooter. For me personally, I really enjoyed that aspect of engaging these non exact range targets. Additionally, to add to the challenge not all the targets were huge 40"+ steel plates or full size IPSC plates, some were much smaller than that. If I recall right, some were as small as 6" wide at the intermediate ranges and about 10" wide at the farther ranges of about 900y or so. Their targets and engagement ranges really tested the shooter's ability in more than one capacity.

Take the conditions that you have of shooting the odd ranges that you have and use it to your advantage. If you can interpolate them and engage them accurately, then shooting exact ranges like most people do will be that much easier for you in the future. You're not only enhancing your technical ability but also your confidence in shooting targets at all ranges. Confidence plays a big part in being able to make the shots and is tied into mindset which is huge.

FWIW, I used an Accuracy1st Whiz Wheel when I was out there and it performed flawlessly for me, even when having to interpolate my DOPE for all the odd ranges that were thrown at us. I'm not affiliated to them in any way or form and I get nothing for endorsing their Ballistic Computer, but I can't argue with the great results I got with it. Like we all know the bullet doesn't lie. I wont use anything else now.

Just my .2c
Be safe

 

[Night Eagle]

Computers work to a degree... The best way to get known dope is to have shot that distance with your ammo. The bullet won't lie.