Ballistic questions

[Aglifter]

A) Do bullets actually rise from the muzzle?  I can't think how, unless the bullet loses rotational momentum in exchange for height -- otherwise, I can't think where the energy would be coming from.

B) Is there a way to lay out the trajectory of a round, or will I have to measure it at various distances?

I got my nifty Garrett safari rounds in 45-70.  Very nicely made, but since I'm using a 26" barreled gun, my velocity will be higher than his published one.  I'd like to work out the drop at various ranges -- really, I'd like a little graph to laminate and keep on me in Africa, so I can check drop at various ranges -- I REALLY underestimate distance -- never realized how close 100yds is -- result from using scopes, and flat shooting rounds, I guess.  I, probably, will chronograph some rounds this weekend -- don't know, after being 70~80 all winter, it's supposed to be cold.

[FireBreather01]

I'll expose my lmited knowledge here to get the discussion started! Bullets drop immediately from the moment they leave the barrel. In fact, going back to physics class long, long ago - if you were to hold a bullet in your fingers, at the same height as your parallel-to-the-earth barrel, and drop your held bullet at the exact time your gun was fired, both would hit the ground at the exact same time, not factoring in friction from the speeding bullet.

Heavier bullets will actually cause your muzzle to rise a bit higher than light-weight bullets, which is why a gun sighted in at say 25 yards with a lighter bullet will print a bit higher with a heavier bullet at the same distance, but that's from recoil - if the gun were held perfectly level and still, the bullet is still dropping.

There are some computer programs that can help you with your charting, but the best they can do is predict what is going to happen based on the information you put into it. But really the best way to do this is at the range with a steady rest and fire your rounds at various distances - then charting those results. That's the way I do it and it's really the only way to become completely familiar with your gun, shooting habits and style, ammo, etc and effectively predict what will likely happen in the field when the time comes.

[R9SCarry]

Yes G at 9.81M/sec is a constant so the force exerted is same whether bullet dead-dropped or fired from same point in space  - if at true 90º to earth surface.

As FB says - many programs are on the net (a search will bring up some) but I also agree, only way for given gun and load is - experiment - logging and make a graph to suit that gun - all else is much too theoretical IMO.

The software solutions give a good estimate perhaps but not good enough I feel.

[sslater]

Aglifter,
Firebreather & R9SCarry have it right.  There's a real simple explanation in the NRA Firearms Fact Book (3rd Edition). The section is titled "Midrange Trajectory".  
Iron sights are about 1" above the rifle bore axis, and about  1.5" above the bore axis for telescopic sights.  Rifles are set up so the line of sight (whether iron sights or 'scope) is not at the same angle as bore.  In other words, you're shooting a bit uphill compared to where you're looking.  But gravity starts pulling the bullet to earth the instant it leaves the barrel.  The apparent rise is from the upward angle of the barrel.

[R9SCarry]

This is a greatly exaggerated and simplified diag I did for someone who wondered how the bullet could be '' on the rise'' - haha - well it is of course only relative to the sight line.