Zak Smith
Member
BHP9,
So what are you after, just penetration? For nonexpanding bullets, the one with the most velocity * sectional density will win. No argument there.
In particular, for a BC of 0.15, a bullet that starts at 800fps will only drop to 733fps at 100 yards, a loss of about 9%. Another bullet with BC of 0.15 shot at 1600fps will drop to 1231fps at 100 yards, for a loss of about 23%.
The point should be obvious: those bullets that rely on high terminal velocity for proper expansion & penetration (combined), so that they do not over-expand and under-penetrate at very close distances, will become more rapidly less effective as the distance increases.
In 5.56mm, M193 and M855 are prime examples: above about 2700fps terminal velocity, they dramatically fragment. Under somewhere in the range of 2200-2500fps, they more or less poke .22" diameter holes.
Contrast to the .45ACP, which is like the 800fps bullet in the example: it only loses 67fps and is probably still within the design range for expansion.
And what happens when these JHP's happen to not expand? They give you what you wanted in the first place: more penetration.
-z
So what are you after, just penetration? For nonexpanding bullets, the one with the most velocity * sectional density will win. No argument there.
For two bullets with the same BC, the one that starts out at 2x the speed of the other will lose a larger percentage of its muzzle velocity at 100 yards than the one that starts out slower.You are absolutely correct and this is why people should not place so much faith in expanding bullets. For example you told of the .45acp bullet designed to expand at around 850 fps but as the range increase the expansion will go down or fail to expand at all.
In particular, for a BC of 0.15, a bullet that starts at 800fps will only drop to 733fps at 100 yards, a loss of about 9%. Another bullet with BC of 0.15 shot at 1600fps will drop to 1231fps at 100 yards, for a loss of about 23%.
The point should be obvious: those bullets that rely on high terminal velocity for proper expansion & penetration (combined), so that they do not over-expand and under-penetrate at very close distances, will become more rapidly less effective as the distance increases.
In 5.56mm, M193 and M855 are prime examples: above about 2700fps terminal velocity, they dramatically fragment. Under somewhere in the range of 2200-2500fps, they more or less poke .22" diameter holes.
Contrast to the .45ACP, which is like the 800fps bullet in the example: it only loses 67fps and is probably still within the design range for expansion.
And what happens when these JHP's happen to not expand? They give you what you wanted in the first place: more penetration.
-z