Your best shot (skill, fluke, or luck included)

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Re: Your best shot (skill, fluke, or luck included)

Post by Jack V » 29 Jan 2015, 12:42 pm

1290 wrote:
Jack V wrote:Light bullets loose their velocity faster than a heavier all else being equal. Over the longer distance the lighter bullet would be affected by increasing drag more than a heavier one . If I am shooting in a down poor at 500 metres I am putting my trust in a 338 LM not a 17 HMR .


Only 2 factor determine the trajectory 1) BC and 2)Velocity

Once you're considering those 2 factors, the mass has zero to do with the calculation, guesstimation, or anything else, why? Thanks for asking.... because the BC is a variable in which the mass has already been considered and is a measure of the rate of deceleration resulting from which over time the gravity will determine the vertical position (trajectory)....there are 2 considerations vertical and horizontal that give the position of the bullet in space (and time :P )...

Sound strange but a 204Ruger 40gr Vmax and a 308win 110gr Vmax, if shot at the same velocity will have very similar trajectories given the very similar BC...

So... I reaffirm, with my limited physics knowledge, that it is the momentum of the bullet that will determine the degree to which a projectile is 'buffeted' by the impact of the rain drop, then consider the divergence from its trajectory whether up, down, leeward or windward, is determined by a time factor, ie. over time so thence it will be the velocity that will determine the magnitude of the divergence....slow=more time to move off course?? Yes? No? what you think? anyone who got this far, thanks for reading, most wont see this line.... :D ;)

No , mass is part of calculating the BC , sectional density is mass , BC is the ability of a bullet to fight drag . High BC will fight drag better than low BC .
That's is why long for the calibre 7mm bullets show high BC's because of their high sectional density figure in the math calculation .
Light for the calibre can't achieve those figures . If what you are saying is correct then all long range snipers would ever need is a 204 ruger . 338 LM would be no better ??? and why would they even bother with a 408 Cheytac ?
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Re: Your best shot (skill, fluke, or luck included)

Post by wayward » 29 Jan 2015, 1:21 pm

Anything I could call a great shot is definitely a fluke :lol:
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Re: Your best shot (skill, fluke, or luck included)

Post by 1290 » 30 Jan 2015, 9:35 am

Jack V wrote:No , mass is part of calculating the BC , sectional density is mass , BC is the ability of a bullet to fight drag . High BC will fight drag better than low BC .
That's is why long for the calibre 7mm bullets show high BC's because of their high sectional density figure in the math calculation .
Light for the calibre can't achieve those figures . If what you are saying is correct then all long range snipers would ever need is a 204 ruger . 338 LM would be no better ??? and why would they even bother with a 408 Cheytac ?


By all means prof. school me on BC.....

Did you read my post at least a couple of times?

TRAJECTORY is determined by the BC and the velocity.As the BC, (being basically, but not exactly a reciprocal (1/x) of a drag coefficient) is a factor representing the slipperiness of the bullet, after that mass doesnt come into it.

You can have say, per my example a 20 and a 30cal bullet with the same BC, and therefore if driven at the same velocity will have the same trajectory.

snipers using 204? how do you get that? Did I refer to kinetic energy? the 30cal comparison would obviously be a light-for-calibre bullet.....
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Re: Your best shot (skill, fluke, or luck included)

Post by Jack V » 30 Jan 2015, 11:25 am

For your example the velocity at say 1500 yards would favour the 110 V-max but not by much but the vertical component of the trajectory would be different by a considerable amount of elevation . Then if the wind was blowing the windage trajectory would favour the 110 v max. All else being equal .
The trajectories only look the same at short ranges and without considering wind .
No single BC can describe a whole bullets trajectory anyway and what BC they quote all depends on what point in the trajectory they chose to quote which is usually the highest one .
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