Thread: Question

If you had a 6mm and .30cal and both bullets went the same speed will they both fall at the same point?

Almost definitely not unless they had exactly the same bc

And weight, more mass means more momentum and better retained velocity for the same BC.

Originally Posted by Spudattack

And weight, more mass means more momentum and better retained velocity for the same BC.

Same velocity but more energy for the heavier projectile right?

Originally Posted by Wildman

Same velocity but more energy for the heavier projectile right?

yes

Originally Posted by Spudattack

And weight, more mass means more momentum and better retained velocity for the same BC.

Nope. BC takes into account weight.





(M is Mass)

Originally Posted by gimp

Nope. BC takes into account weight.


Attachment 9023


(M is Mass)

Ah, fair enough, never seen that equation before!

I take it Cd is drag coefficient? What are the A, p and l?

Originally Posted by Spudattack

Ah, fair enough, never seen that equation before!

I take it Cd is drag coefficient? What are the A, p and l?

BC = ballistic coefficient as used in physics and engineering
M = mass
A = cross-sectional area
Cd = drag coefficient
ρ (rho) = average density
l = body length



Bullet BC calculation is different but still takes mass into account.



BC = ballistic coefficient
SD = sectional density, SD = mass of bullet in pounds or kilograms divided by its caliber squared in inches or meters; units are lb/in2 or kg/m2.
i = form factor, i= CB/CG, (CG ~ 0.5191)
CB = Drag coefficient of the bullet
CG = Drag coefficient of the G1 model bullet
M = Mass of bullet, lb or kg
d = diameter of bullet, in or m

That's what I was thinking but I couldn't think of a easy way to ask Google so you lot had to do.

JBM Toby

However Toby, in a vacuum they would theoretically. Its pushing through the air that makes the difference

You wouldn't be able to shoot in space because there is no oxygen?

Originally Posted by Toby

You wouldn't be able to shoot in space because there is no oxygen?

How do you think they move the ISS and satellites about in space. They use liquid oxygen but there is a bit of air (O2) in a cartridge so I'll bet it will still maintain velocity.

The Straight Dope: Would a gun work in space?

Originally Posted by Toby

You wouldn't be able to shoot in space because there is no oxygen?

Gunpowder contains an oxidising agent, I don't think it requires any external oxygen.

How does a compressed load fire then Toby?
Google explosives and how they work(I dont want a visit from the feds) Im pretty sure most explosives generate there own oxygen but have been wrong before.