Where do you get your DOPE?

[PathFinder]

Tonight I took my H-S Precision PLR 300 WM (26" barrel) out to really stretch its legs. I'm shooting 208 Hornady BTHPs over 77.5 gr. H1000 and a Rem. 9.5M primer. I don't have a chrony so I took a wag at my velocity (2950). For a ballistics calculator I'm using Litz's Applied Ballistics, and using the numbers from the bullet library for a G7 BC. At 700 yards, Applied Ballistics gave me .5 MOA too much correction for drop. At 1000, it gave me 1 MOA too little; I corrected my velocity to match at 1000 yards (to 2850), and moved back to 1450. I initially dialed the 44.5 MOA given by Applied ballistics and fired. The shot was way low. I dialed to 48, and made a hit. Hit the target frame on the next shot, then made another hit. Then one went way high (no idea why). One last shot before dark was another hit.
From this I've realized that I need a more reliable source for data. I don't think the problem lies entirely with Applied Ballistics; probably more with my ability to use it. There is also possible error in the BC (at lower velocities), the scope's dials (Viper PST) and my input velocity. I'd make a simple card, but the calculator is great to take into account spin drift, coriolis, shot angles, and atmospheric conditions. I'm thinking hard about a Whiz Wheel as well. Where do you get your dope (pun intended) and why?

 

[RosinBag]

The most accurate way to get your dope is to shoot it in. Zero your rifle, shoot in a mid range and a long range distance. Then take that info and input it into a ballistics program. You will need to manipulate your BC and velocity to get the dope to verify.

Take into account what you and your rifle is capable of at 1400 yards. If your rifle shoots one MOA groups at 1400 that is the same as 14". So unless you break every shot perfect, missing by a couple feet at that distance is like missing by 1.5" at 100 yards. The further out you go the more the environmental factors will have also.

 

[mtnwrunner]

Tonight I took my H-S Precision PLR 300 WM (26" barrel) out to really stretch its legs. I'm shooting 208 Hornady BTHPs over 77.5 gr. H1000 and a Rem. 9.5M primer. I don't have a chrony so I took a wag at my velocity (2950). For a ballistics calculator I'm using Litz's Applied Ballistics, and using the numbers from the bullet library for a G7 BC. At 700 yards, Applied Ballistics gave me .5 MOA too much correction for drop. At 1000, it gave me 1 MOA too little; I corrected my velocity to match at 1000 yards (to 2850), and moved back to 1450. I initially dialed the 44.5 MOA given by Applied ballistics and fired. The shot was way low. I dialed to 48, and made a hit. Hit the target frame on the next shot, then made another hit. Then one went way high (no idea why). One last shot before dark was another hit.
From this I've realized that I need a more reliable source for data. I don't think the problem lies entirely with Applied Ballistics; probably more with my ability to use it. There is also possible error in the BC (at lower velocities), the scope's dials (Viper PST) and my input velocity. I'd make a simple card, but the calculator is great to take into account spin drift, coriolis, shot angles, and atmospheric conditions. I'm thinking hard about a Whiz Wheel as well. Where do you get your dope (pun intended) and why?

Pathfinder, IMO and it works for me-------------is actual field data. I am lucky in that I can shoot to as far as I want to off my front porch. I measure my drops out to 1000 in 100 yard increments with a tape measure and then just find a program that matches the drops as close as I can get it. It does take time but man, it is worth it. I've tried various different programs and some are better than others or maybe I should say that some match my profile better than others. I currently use Shooter and Hornady.

Randy

 

[GLB]

Ballistic programs are a good start provided that you put good information in it, but it needs to be trued with you and rifle combo in the field.

 

[Formidilosus]

Provided that all of the info put into the program is correct, the data it gives will be correct. I would expect to see no discernible variation out to around the 1,000- 1,100 yard range with your cartridge/load. Obviously you can't input very good data as you don't know the velocity, however if you have a solid zero, then you can backwards track it by shooting at distance to get the drop. Then tweet the velocity in AB to match the acti drop.

Right off the bat you need to do a tall target test on that Vortex. It should always be done with scopes, however Vortex scopes have lots of issues and it's highly likely that it will show some. By tall- I mean to the limit of the scopes travel. At least 50 MOA based on your shooting.

Also-

How good is your zero? No really. Everyone thinks they are zeroed, yet zeroes being off is more common than not, and causes a lot of errors.

 

[PathFinder]

I found the main source of the error last night. My Leica that I bought the day before came in metric mode; it was ranging in meters. I converted the distances to yards and ran the data through AB again, and it came out very, very close. I input my actual drops into the velocity correction tool in AB. Haven't had a chance to shoot again yet, but I'll do some more shooting to make sure it's dead on. My zero is great. I was really particular about it.

 

[charvey9]

I use JBM ballistics calculator online to print range cards. Getting accurate velocity is very important in the calculation. A decent chrono is a good investment.

http://www.jbmballistics.com/ballistics/calculators/calculators.shtml

 

[land cruiser]

Handloads, magnetospeed chronometer, litz books for bc, kestrel to dial in and work on true drop and Leica HD b to hunt. Practice every month to learn wind calls. It's been 3 years and I am still learning the wind portion

 

[bates]

You need to get a good chrono - magneto speed or the new lab radar when it comes out, it will pay for it self and save lots of time and wasted rounds, you need to know your speed as well as your ES, no chrono is 100% accurate but it will get you close for the money the magneto is hard to beat.

then I would suggest a kestrel that measures Density altitude, you could kill 2 bird and get the Applied Ballistics version and be set
then make cards for back up. I run jbm cards in 500 ft. Density Altitude increments

also make sure your zero is dead nuts

 

[KMD]

With the technology and data sources available nowadays, proving dope is easier than ever.
First, I use a Magnetospeed to get a decent velocity input to start with.
For ballistic solver, I've been runnin' Ballistic AE. It has Doppler proven "Litz" drag curves for many popular LR bullets. I use "Litz" drag data, when it's available. Or take measured BC from Applied Ballistics book & input that, manually.

Ballistic AE also allows for "zero offset". IF your rifle's zero POI is off even by 1/10", you can input that into the solver & correct for it.

Using Kestrel 4500, I get a measured DA on station to input. Ballistic AE can also pull DA from nearest weather site, given cell service is available. But it is always more better-er to use actual measured DA, at your shooting position.

With that info, I shoot 500-1000yds & note any vertical discrepancy between calculated dope and target impact. If vertical is off, Ballistic AE has a "velocity truing" feature, where you simply input the vertical difference in inches, hit 'calculate', and the program will 'true' your velocity for you...

To give an indication of how close a program like Ballistic AE can be, I used the "Litz" drag curve for a 130HVLD in conjunction with a 3204fps MV avg from my Magnetospeed. After proving dope out to almost 1100yds, the 'trued' velocity Ballistic AE calculated turned out to be 3196fps...

Remarkable stuff!!!
Gone are the days of runnin' Exbal on a Palm pilot & fudging BCs and MV to get things to jive!

 

[Take-a-knee]

EXBAL and an el-cheapo Crony have been dead-nuts (if you put in accurate environmental data) out to 650yd. I can't shoot any further without a LONG drive.