Originaly posted by phrigid
Very good, Garand. You have proven and made public our misconceptions LOL. So much for us Nuke security guys being professional, huh?
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In fact I have. You may know how to secure the nuke stuff, but I guess a knowledge of ballistics is not required.
If you have a barrel perfectly level (in relation to gravity) the bullet will not rise above the bore line. It is the alignment of the sights and the fact that in most situations that the barrel is tilted slightly upwards in order to get the sights alignend with the target that causes the rise.
Here is the data for Sierra .222 Remington 63 Gr SP starting at 3100 fps
Range Vel Energy TOF Drop
0 3100 1345 0.000 0
25 3013 1270 0.024 -0.10
50 2930 1201 0.049 -0.43
75 2848 1135 0.075 -1.01
100 2769 1073 0.102 -1.87
125 2692 1014 0.129 -3.00
150 2617 0958 0.158 -4.44
175 2544 0906 0.187 -6.19
200 2473 0856 0.217 -8.27
225 2405 0809 0.247 -10.72
250 2338 0765 0.279 -13.53
275 2273 0723 0.312 -16.75
300 2210 0683 0.345 -20.38
325 2148 0646 0.379 -24.46
350 2088 0610 0.415 -29.01
375 2030 0577 0.451 -34.06
400 1974 0545 0.489 -39.63
425 1919 0515 0.527 -45.76
450 1866 0487 0.567 -52.45
475 1814 0460 0.608 -59.82
500 1763 0435 0.65 -67.83
See... NO RISE. Now if you zero at 250, your line of aim is below the flight of the bullet, but your sights are above. So this rise you think you see is coming from the fact that the line of aim and the bullet path cross 2 times, once when the line of aim crosses below the flight path and the second at the point of aim. The bullet will appear to rise between the first cross and the point of aim, but the bullet is in fact dropping, what your are noticing is the widening and closing of the differance between these two lines.
That is how you can have a 25M zero good at 250 with some weapons, those 2 ranges are the 2 points where the line of aim and bullet flight path cross. The bullet does not climb, your line of aim just intersects it, drops below it, then intersects again.
Edited for clarity.