Ballistics programs dont match actual traj.

[brickeyee]

Did you fire on a 200 yard target immediately after firing on the 300 yard one?
Is the BC for the bullet you are using valid over the speed you are using it?
While you may not be able to find a single parameter change that explains your results, all you need is a chain of discrepancies to stack up the wrong way and the results become GIGO (Garbage In, Garbage Out),

 

[dennisH87]

The range finder i have is very accurate. It's a Nikon 440. It's only a 1X so it's not hard at all to keep it steady. and the button can be pushed and held down for continuous ranging, even on moving targets like cars. So I am confident it is 300 yards. I need to find a place to shoot 300 yards and try it again to confirm the data.

 

[dennisH87]

ya, i sighted it in at 200 then moved the target back to 300 yards. The bullet is a 60gr. V-Max with a BC of .265.

 

[brickeyee]

You need to fire on the 200 yard target AGAIN after the 300 yard target, and preferably without a large time lag so conditions remain the same.

You also need more than 3 shots at each range to have a statistically valid measurement of the center of the group unless your groups are significantly smaller than the discrepancy you are chasing.

 

[Zak Smith]

Ballistic programs work provided you feed them correct input data. They work well enough to make first-round hits at 700+ yards provided an accurate MV and solid 100-yard zero.

In other words, if it's giving you bad data, it's almost a certainty than you're feeding it bad input data.

-z

 

[jim147]

I got interrupted one my earlier post and then out shooting all weekend.
Brickeyee hit what I was starting.
Is it a level 300 yards?
Was there any wind giving lift?
You don't know exact MV.
Adjusted altitude.
You won't find 4 inches in any one spot. But a stack of variables can really add up as distance increases.

 

[Win52D]

One other thing comes to mind...a long shot really...what is the BC of the bullet...if the actual BC is significantly higher than what you are plugging in to the calculator it may account for some of the difference.

 

[30Cal]

I'm not a huge believer in ballistics calculators, but if you can't get it to agree within about a minute with "real" data, then you're doing something wrong.

I'm thinking either you're distances aren't right or your rifle did something between 200yd string and 300yd string.