Ballistic calculator differs from range tests-Why?

[charliebrown1999]

Shooting my Savage Model 12 VLP 26inch heavy barrel caliber 243 Win using PPU 90gr SP ammo with muzzle velocity of 3100fps. Shooting at 200yds hitting 6inch plate. Had to dial .9 MILS of elevation about to hit 8 inch steel at 300yds. Scope is Athlon Argos BTR 6x24x50 MILQuad FFP. Turrets are .1MIL increments. Hornady ballistic calculator says if zeored at 200yds your drop at 300yds is only 6.7 inches therefore you only need .6 MILS come up. Yet i needed to .9 MILS of come up which is about 9.72 inches to hit at 300yds.
I used the muzzle velocity that is on the box of ammo. Here is the puzzling thing- according to the ballistic calculator to have a drop of 9.72 inches between 200 and 300yds the muzzle velocity would be 2200fps. What the hell is going on here???

 

[spmcpeek]

Have you actually used a chrono to get your muzzle velocity or are you using what's on the box of ammo?

 

[charliebrown1999]

Have you actually used a chrono to get your muzzle velocity or are you using what's on the box of ammo?

using what is on the box

 

[spmcpeek]

So your actual MV is lower than what it says on the box.

 

[Huskerhunter]

Sometimes just easier to true it up than go down the rabbit hole of "why"....

 

[charliebrown1999]

Have you actually used a chrono to get your muzzle velocity or are you using what's on the box of ammo?

using what is on the box

 

[Jack Master]

did you verify the 3100 fps? could your muzzle velocity be different?
Did you check yo scope tracking?
was the information on the box in the same environment your are in? Elevation, Temp, Pressure.

When you get into long range shooting you'll quickly find what is on the box is what was tested with thier test fixture, not your rifle. This is why we shoot the distances and then make the computer match what we shot. In this case, calibrate the calculator to match the .9 mils.

 

[Steel head]

True you’re app to your actuals.
simple.

 

[Dthomas3523]

1: MV is only what box says on rare occasions

2: .3 difference can be many things or a combination of things. Your zero is almost never perfect with .1 mil turrets. Did you measure optic height? Then there’s shooter error, scope tracking, mirage, light refraction.....etc etc

 

[charliebrown1999]

i have

So your actual MV is lower than what it says on the box.

i have updated my thread. In order to have a 9.72 inch drop (.9MILS at 300yds) the muzzle velocity have to be 2200fps.

 

[charliebrown1999]

1: MV is only what box says on rare occasions

2: .3 difference can be many things or a combination of things. Your zero is almost never perfect with .1 mil turrets. Did you measure optic height? Then there’s shooter error, scope tracking, mirage, light refraction.....etc etc

i have updated my thread. In order to have a 9.72 inch drop at 300yds requiring a elevation increase of .9MILS the muzzle velocity of my ammo would have to be 2200fps. That does not sound logical. I think it is the cheap ass scope.

 

[charliebrown1999]

True you’re app to your actuals.
simple.

you are absolutely correct. those ballistic calculators are only ball park estimates and i have taking them as the precise dope. what fool am I.

 

[Steel head]

you are absolutely correct. those ballistic calculators are only ball park estimates and i have taking them as the precise dope. what fool am I.

No
They can be valuable tools once you get them in sync with what your bullets are telling you.

You don’t have a known speed or tested BC but if you get your app to match your actuals with known conditions then you’d be surprised at how well It can fill in the gaps or adjust for different conditions.

 

[spmcpeek]

It's a calculator, not a psychic. It is only as good as the information you give it.

 

[dimar1492]

Sounds like mechanical errors. Sight Height, 100yd zero, scope adjustment error, something like that.

Truing your chart to make up .3mil at 300 will likely fuck the rest of your chart. The chances that your velocity is actually that slow or the BC is that far off is slim at 300. At a minimum you need to see how low you are at a second distance to see if it's a constant or it gets worse. This will eliminate some of the variables.

 

[Lowlight]

Look up Weaponized Math to dope a rifle, then you take those results and use it for a truing a ballistic calculator

New shooters have no clue how to dope a rifle nor do they understand the inputs and what is needed, Weaponized Math walks them through the process so they understand what is happening.

A ballistic calculator is not a tool for the uneducated in this respect, clearly we see post after post with these same questions that only confuse the end user. We created a worksheet for our classes that make it super easy. It uses verified data to move you downrange, in a way that is easy to understand.

You don't need Sight Height, BC, Bullet weight, MV, there is no drifts as it's included in the shot already, we doped gravity from shot to shot and all bullets regardless of weight fall the same way, gravity, drop a rock, drop a basketball they hit the ground the same time.

You will be within .2 at the most, none of this accounts for poor fundamentals, but this works, take your 300 data, multiply by 1.75 gives you 400, should put you on the water line, take 400 ending data multiply by 1.45 hit 500 on the line, etc,

Search: Weaponized Math Worksheet

 

[Dthomas3523]

you are absolutely correct. those ballistic calculators are only ball park estimates and i have taking them as the precise dope. what fool am I.

Calculators are NOT ballpark if you use them correctly.

 

[Dthomas3523]

Your post is also confusing.

Did you zero your rifle at 100 or 200?

From that zero, how much did you have to dial into your turret......from zero, to hit 300yds?

 

[b6graham]

zero at 100 first off

box MV can be a joke. I've had hornady 140eldm at 2700 (box at 2710) and I've had it at 2830 from a different gun

also, a 6" plate is quite a zeroing target. if you're low at 200 and high at 300 that's a potential for 7 inches of drop just in the target size

 

[Lowlight]

This is the point, until verified with shots on target, a ballistic calculator is a prediction that requires accurate information in order to work.

you cannot match a rifle to a calculator, the calculator must be matched to the rifle, hence truing.

garbage in, is garbage out, and generic values like information off the box can be considered garbage in most cases.

start with Weaponized math, dope the rifle to distance, then you can use that data to easily set up and true the calculator, most people reverse this process and struggle to not only understand the process, but believe the calculator values are more important than their shots, which they then second guess.

the success we see with weaponized math across a variety of students, locations, and calibers, is beyond anecdota, it works and makes life easier.

 

[Steel head]

Calculators are NOT ballpark if you use them correctly.

 

[charliebrown1999]

Your post is also confusing.

Did you zero your rifle at 100 or 200?

From that zero, how much did you have to dial into your turret......from zero, to hit 300yds?

zeroed at 200yds then needed .9MILS to hit at 300yds

 

[charliebrown1999]

Look up Weaponized Math to dope a rifle, then you take those results and use it for a truing a ballistic calculator

New shooters have no clue how to dope a rifle nor do they understand the inputs and what is needed, Weaponized Math walks them through the process so they understand what is happening.

A ballistic calculator is not a tool for the uneducated in this respect, clearly we see post after post with these same questions that only confuse the end user. We created a worksheet for our classes that make it super easy. It uses verified data to move you downrange, in a way that is easy to understand.

You don't need Sight Height, BC, Bullet weight, MV, there is no drifts as it's included in the shot already, we doped gravity from shot to shot and all bullets regardless of weight fall the same way, gravity, drop a rock, drop a basketball they hit the ground the same time.

You will be within .2 at the most, none of this accounts for poor fundamentals, but this works, take your 300 data, multiply by 1.75 gives you 400, should put you on the water line, take 400 ending data multiply by 1.45 hit 500 on the line, etc,

Search: Weaponized Math Worksheet
View attachment 7396136

QUOTE]
Thank you for responding with great information. I will print out this data and use it .

 

[Dthomas3523]

zeroed at 200yds then needed .9MILS to hit at 300yds

Something is very wrong. That’s usually from 100 zero to 300.

 

[b6graham]

Something is very wrong. That’s usually from 100 zero to 300.

zeroing on 3moa steel. always a good idea

 

[Lowlight]

When zeroing on steel always use a defined waterline on the plate so you hit the line to confirm point of aim, point of impact