Home Forums Reloading Reloading Software Changing BC values in QL and QT

I want to change the way BC is used for QL and QT using Bryan Litz's G7 values instead of the usual G1 value we are all used to working with.

Another problem is doing it for only a hand full of bullets used for long range since I do not have G7 values for all bullets. Anybody got a clue as to what I can do?

I doubt that changing the numbers alone will give you better results by any criterion.

I'd expect the software to continue to make its calculations as it normally does but applying its G1-based calculus to your ersatz values based on a different model from the G1. I can't imagine that the result would be anything but useless gibberish.

Using unconverted English units in a metric equation � for a parallel example � gives utterly useless final figures.

Groups get bigger the farther away the target is,* so theoretically predicting a trajectory is an approximation anyway � precisely predicting a single trajectory is impossible. Only an approximation of an presumably "typical" trajectory is possible � within certain fairly loose limits.


*(Each bullet flies on a slightly different trajectory � in part because it leaves the muzzle at a velocity that may not be even close to that load's [i]average velocity � which itself may be only an imaginary, calculated figure.)[/i]

You can do that in Quicktarget Unlimited, but not in old Quicktarget.
The old Quicktarget uses only G1 drag table, but QT Unlimited is free of G-tables, it still is able to use them, but it uses normally a bullet specific drag function, i.e. Radar drag data. You can open the bullet file using the bullet-caliper icon, specify drag function, here G7. Then enter the BC(s). You may change the bullets name with an remark to G7 (ie. .284,175, Berger XYZ G7), because this bullet data is then no longer for old Quicktarget. Then save the changed entries. Thats all. Use this bullet with QT Unlimited. When you recall this bullet, QT Unlimted loads automatically the G7 function. I personally do not like G-functions - it is technics from yesterday.
We are just providing Radar data for Lapua bullets - hope to show them at ShotShow 2009.

No doubt radar data woud be better than G7 data. Are Lapua bullets the only ones that you plan on supplying radar data for?

Can the old QT be upgraded to the unlimited version, and if so, what is Neco charging for the upgrade?

Yes, it's possible. Please contact NECO.
Lapua is at this time the sole manufacturer who is testing civil match bullets using a Weibel 1000 radar and willing to generate drag data this way, so far I know.

The way people calculate BC has a component part of velocity. If the velocity is changing from point blank to any distance away from the muzzle, then that has to mean a change in the BC is calculated.

Why does it take a Doctor to get you to understand that? Once again it takes Ken to come on and explain that to us?

Using a radar range to give accurate real world BC and trajectory is the only way I know to cut through the BS of BC.

I'm still disappointed that BC has to be calculated by comparison with data from another projectile rather than comparison with the subject bullet's performance in some "pure" situation � in a vacuum, for example.

Only a G1 flies like a G1. Only a B7 (if there were such a bullet) would fly like a B7 � and it'd fly like no other bullet. Therefore, any "calculation" of the effects of drag and gravity on any bullet's velocity and trajectory is a very rough approximation � an estimate that seems to offer more precision than it can deliver.

Comparing the performance data of subject Bullet A and subject Bullet B by the same calculus can be useful as long as we realize that both sets of results are imprecise estimates based on impossibly imperfect comparisons.