9mm.....extra 100 fps....what does it do?

quote:

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1525-1316=209

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damn, what the hell is wrong with me?

It goes a 100 feet per second faster

In the example rounds you gave here (+P), the main reason for the additional speed is that in the 16" barrel, most, if not all, of the powder in the round has ignited in the barrel where in the 4" it has not. Complete powder burn is what most people who reload for
accuracy try to achieve. Powder burning outside the barrel after
the bullet is gone does no good. Although some like a big fireball
on the end of their gun. In a
combat or self defense situation, a
fireball may disorient or even
temporarily blind the shooter
making followup shoots difficult. In
my opinion, the most useless gun is a 2 1/2" 357 Magnum for this
very reason. I'm not sure about all
the effects of energy or "stopping
power" 200 fps will have. A lot of
it is bullet design. The more
contact with the barrel a bullet
has, the more accurate it should
be in theory but that also depends
on bullet weight and design. As a reloader I can say that faster is not always the most accurate. Bullet weight and powder charge have a lot to do with accuracy.

Relatively nothing.

Wouldn't longer barrel help achieve better twist as well or would this have any effect? I was thinking it would.