Norma 75 grain V-Max bullets .243 and my drop charts.

[robbobsam]

Hiya Guys,

After trying many different types of bullet in my rifle I have found that Norma 75grain V-Max are the most accurate for zeroing. They will give me .5" groups at 100yds.

I am now trying to generate an accurate drop chart for longer range shots and I am struggling.

I have tried using 2 different ballistics software sites and they are both giving me different results.

These are the ones I have tried.

External Ballistics Calculator

Berger Bullets

The berger bullet ballistics software asks for a G1 or G7 setting and I believe these relates to whether the bullet is flat base or boat tailed. As the V-Max is boat tailed I selected G7.

Why do the figures not match up.

I have tried both sets of data produced with both software programs and neither is particularly accurate in the field.

What is going wrong.

This evening I managed to get a new long range record for myself, I managed a 450yd rabbit using the drop chart from the big game software, but I am sure the rabbit was killed by the bullet ricochetting up from the ground in front of the rabbit as I saw a puff of dust prior to the rabbit keeling over. This is particularly strange as the big game software works on the principle that the bullet is flat bottomed and if I had used the drop chart figures from the Berger bullet software with G7 settings it would have dropped a lot shorter.

Can anyone offer any assistance.

How accurate are the stated velocities on the Norma Bullet box. Could that be the issue, should I first chrono the bullets in my own rifle and start again.

 

[Varminator 911]

Man I've never heard of a Norma V-Max. Are you sure it's not Hornady? But they don't make a 243 75 grain V Max either, I don't think. So you've got me stumped there.

Most of the bc you will see listed are G1 bc. It doesn't have anything to do with a boattail or not. Berger is the only company I'm aware of that uses the G7 model. And they usually list both G1 and G7.

You just need to get the right bc, know which model bc it is...most likely G1, and enter the velocity. That will give you a fairly accurate drop chart.

 

[justgoto]

Yes, you need to chronograph them yourself to be more precise.

I chronograph my velocity, then a general idea from the Hornady Ballistic Calculator. I will take my rifle out and get a zero at a number of different ranges and write down my scope settings for each distance. I'll use that for my drop chart.

A lot of members here have a program on their hand held devices that figure everything in the field. I'm not quite sure how it works exactly, but I think it works wonderfully.