Sierra bullet question?

[foxwhistler]

I was just wondering out of interest why the Sierra BK has a different ballistic coefficiant when the velocity is increased,while no other manufacturers list this?
Any help will be appreciated.

[WrzWaldo]

I was just wondering out of interest why the Sierra BK has a different ballistic coefficiant when the velocity is increased,while no other manufacturers list this?
Any help will be appreciated.

Because the other manufacturers would like you to believe that the laws physics do not pertain to their bullets.

I'll post more after I've gathered my thoughts (and the boss quits pestering me).

Edit: Call me lazy.

The transient nature of BC's

Variations in BC claims for exactly the same projectiles can be explained by differences in the ambient air density used for these BC statements or differing range-speed measurements on which the stated G1 BC averages are based. The BC changes during a projectile's flight and stated BC's are always averages for particular range-speed regimes. Some more explanation about the transient nature of a projectile's G1 BC (it rises above or gets under a stated average value for a certain speed-range regime) during flight can be found at the external ballistics article. This article implies that knowing how a BC was established is almost as important as knowing the stated BC value itself.

For the precise establishment of BC's or maybe scientifically better expressed drag coefficients Doppler radar-measurements are required. The normal shooting or aerodynamics enthusiast however has no access to such expensive professional measurement devices. Weibel 1000e Doppler radars are used by governments, professional ballisticians, defense forces and a few ammunition manufacturers to obtain exact real world data of the flight behavior of projectiles of their interest.

http://en.wikipedia.org/wiki/Ballistic_coefficient

[foxwhistler]

Thanks for the reply.I`ve read it about 5 times so far,and i think i`m beginning to understand it.Another 5 read throughs and i should be there.Mind you the wife has allways accused me of being a bit slow! I`m beginning to think she`s probably right.