Ballistic calculator issues

[Arapaho]

I can tell you from experience that double checking your data that you entered into the app is critical. I went to shoot a rifle a few years ago at 1000 yards and when I checked my ballistic app (Strelok), the dope it called for was unbelievable so I dialed over double what it called for and walked it to the target. Later that night, I checked the app and realized that I forgot to put the point before the BC (such as 576 instead of .576). One little mistake changes everything. Luckily I knew instantly something was off and dialed accordingly but it took me a while to figure out what the issue was. Of course, I'm not the brightest rock in the box LOL.

 

[PNWdude67]

Why not tell us the numbers? Scrolling through it appears you're not shooting past 600 yards? So with a 100 yard zero maybe a 10.5 MOA come up?? That's just mental some quick math in my head. What weee the distances and the MOA discrepancy between the scope and your calculator. One simple check is try a different calculator. But you should be able to tell what's up just from DOPE on your other rifle systems. 600 yards there's not much to go wrong and it's not far enough to true BC. If the tracking is way off on your scope that close then it's pretty bad and unreliable I would think for a hunt. I would take a scope you trust from another rifle and zero it. Again another way to test if it's the scope or your app.

 

[Greyfox]

It would be helpful to understand the degree of difference between you BC outputs and actual POI.
Given you have proven your BC calculator/results with other rifles, I would rule this aspect out of the equation(although it may still be wise to re-check the inputs). Just my viewpoint, but if the scope tracking is suspect, particularly a scope that has not been formerly tested/proven for tracking accuracy and precision, my preference with a new rifle/load is to switch to a scope that has been verified. While this may not always be a practical for some, but it's certainly more expedient in trying to diagnose the problem, and quickly eliminates a variable….Surely if time is a factor. If your scope checks out to be the issue on Saturday, you still will not have confirmed your ballistic information. IMO.

 

[floyd kittrell]

If you are as OCD as I am, the variances in ballistic aps and on range shooting WHYS can drive you nuts. I use the data from ballistic aps, print them out as a theory or reference to dial up, to get me close , shoot the different yardages in 100's out to max range that my selected bullet will fully open up , I then take the actual data and make my pocket card and print a card and tape to the stock which has been confirmed , proofed, in the field. I have given up on all the WHY's , just proof it at the range make your dope card and go hunt. JMHO

 

[Tuffcountry]

So posted BC is just Posted… if you're confident in your scope height and your velocity, there is only a handful of other variables in the equation. Temp, air density, wind, elevation, consistency of load work up, factory or hand loads, SD and ES ext. I do not rely on posted BC. It is based off an average of barrel length, velocity, powder charge ext. Typically sea level elevation. Barrel twist, velocity, elevation all play a role in your ballistics being correct. I personally do not true my ballistics inside of 800 yards. 650 on most ballistic calculators is very close after 650 you start to see what I refer to as the parachute effect on projectiles. Adjusted BC or velocity values will true your Drop chart. The effects on doing this are very minimal if any inside of 650. If your scope is tracking properly, then you need to adjust the BC value of your ballistic calculator to correspond with what your true dope is on your scope. Trust what you see, not what a computer tells you.

Great explanation top pin. On that subject is also the fact that the BC of a projectile is changed once it is fired out of the barrel. It is now in so many words deformed with rifling grooves therefore lowering its BC slightly and changing its ability to dissipate the atmosphere in flight which will show up more drastically down range

 

[KsKevin]

1) 100yd tall target test to confirm scope
2) true ballistics at 600+yds for bc / mv

Should be about that simple

 

[Cope2115]

Hey man, most of the time the results don't line up. Ap projectiles BC degrades as it flys and most Ballistic Calculators do not compensate for it. This is why you have to "true" you calculator. Just google "truing your ballistics solver".

 

[azarcher10x]

I'm not any kind of a long range target shooter, but I want the best accuracy for hunting to the maximum capability of my cartridge choice. That's where I test for accuracy. In my case, it's 800- 900 yards for my 300 RUM. I use two apps for my ballistic calculations. Ballistics Arc and the Zeiss Hunting App to sync to my binos for hunting. I don't worry about BC, other than inputting the manufacturers estimate. I do the basic weather inputs, but then go off the absolute pressure from my rangefinder. (Zeiss RF binos) I would recommend a 100 yards zero, and you can then do a tall target test for peace of mind. I have yet to find a scope that didn't pass this within a click at 30 moa. After that, I shoot an 800 yard target for zero, and let the app calculate a true muzzle velocity number from that. Once I'm there, everything jive's!

 

[Longshotjames]

If you are using a Chronograph (not radar or magneto) It could lie to you depending on condiditons. I once trued a load for a 7rem mag that was actually 200fps faster than than my Chrono told me. I fixed the speed in my calculator and everything matched up and proved correct out to 1mile. My dad still has that rifle and using the same data for years now.

Point is that some part of your data may not be correct. By checking it with actual POI you can true in your data to be accurate, especially out to 600. The mean Longrange gremlins don't start until after 600yd...MHA HA ha ha

Id check velocity and Barometric pressure as 2 most likely factors to be off.(assuming you have a solid zero)
James

 

[mooseskinner]

Ditch the Strelock, switch to Hornady 4DoF w/ zero angle.

I agree. I shoot F=Class to 1000 yards and Hornady 4DOF with zero angle is heads and shoulders above a BC app. You can change environments without having to rezero your rifle. If you input the current environmental factors, the rifle will shoot to your zero whether it is 90 degrees at sea level or 20 degrees at 10,000 feet.

 

[Mikecr]

the rifle will shoot to your zero whether it is 90 degrees at sea level or 20 degrees at 10,000 feet.

Do you mean the software corrects your entered zero internally?
That you qualified entered zero with air density attributes (which must be stored) that zero was based on.
Then with new air density, the software adjusts for new zero.

All in discussion definitely matters at 600yds or below for some of us.
I would have a terrible kill percentage on groundhogs if not for accurate external ballistics.

 

[MontanaJack]

Some ballistic programs allow inputs for both altitude and atmospheric pressure. This leads to confusion because then you don't know which value the program uses or it it used both. You might see if your data and actual targets align better with one of the online ballistic programs like Hornady or Leopold. How are you getting distance data: range standards or electronic device? Most rangefinders allow a plethora of options for units and some come out of the box with some metric units activated.

 

[cgarb]

Rangefinder verified distance. It's flat where we shoot, angle shouldn't be a factor in the range.

 

[A/1-61]

Getting ready for a cow elk hunt. Taking my 7mm Practical, 180gr ELDM over 87grs of US869 powder. 5 shots across my magnetospeed showed 3063,3067,3071,3097 and 3089. Avg of 3077 is what I got. My issue is if I input those inputs into Strelok the data it puts out don't jive with actual shooting results. I'm just charting my actual come ups in MOA and going to go with actual shooting results rather than calculated data but I'm not sure why? Strelok data works for my 308 and my 30-338 Winchester, but this rifle has always seemed to not line up with what the info says. I may perform a box tracking test on my scope. That's the only thing I can think of is the 1/4 MOA clicks are not moving 1/4 MOA. It seems to return to zero fine though. If I dial to a yardage and come back to zero my 200 yard zero seems to repeat. Nikon X1000 Black 4-16x50. Think I'm barking up the right tree?

I have run into the same issue with my 7mm STW. It could have to do with BC, twist, the actual rifle your using, etc. I have the luxury of owning property at sea level in coastal Maine where I have a range that goes back 600 yds on my property. I start out by inputting my ballistic software for a starting point, then I get actual data at 100, 300, 500, and 600 yards. I use the actual shooting data to develop a new curve by tweaking the input values for velocity, BC, in my Sierra software. I do whatever it takes. When I finally come up with a new curve that mimics my actual shooting data, I just adjust the elevation from sea level to wherever I'm hunting and make a range card for the MOA adjustments of my ballistic turret. This year, I hunted Utah at 10,000 ft above sea level. When I got to Utah, I found a range in Vernal at 6000 ft. This was the final test of my adjustments. I fired at steel elk silhouette targets at 870 yards and 1080 yd and hit the center of the vital zone of both targets. Bottom line, Nothing can replace your "at the range data".