or is it mainly for looks? I must admit it looks better with one than without. Any builders or buffs out there that know more than I?

If you mean the groove down the center of many edged weapons blades, that is properly known as a [i][b]fuller[/i][/b]. Its purpose is to lighten the blade. Thats it [:)]

G2

Yeah, thats the one. I always heard it refered to as a blood groove.

On sword-length blades, fullers serve to lighten the blade while retaining stiffness.  Like a fluted rifle barrel, you end up with a blade that is stiffer than an un-fullered blade of the same weight.  On knives, they serve basically the same purpose, but the amount of weight saved is usually trivial, so they are mainly for appearance's sake.  The so-called "suction" that is supposeed to hold a blade in a wound after a thrust does not exist in my experience, so any stories about fullers/blood gutters/blood grooves breaking that suction to make withdrawing the blade easier should be taken with a grain of salt.

It is if you're runnin around stabbing people and you want to get the knife back in a hurry, relieves the suction when pulling it out. or thats the wives tale I like to believe

It helps alot with those relly bad hangnails.

Only for Blackula

Removing metal from a piece can not make it stronger except maybe when very heavy pieces are concerned, as in I-beams.  

Please note he says "of the same weight".

Removing metal from a blade or a rifle barrel can [b]not[/b] make that same piece any stiffer.

However changing the design to include the fluting or fuller can allow more metal to be concentrated in the areas critical to strength.

This allows you to make a stronger, fluted, piece with the same weight as the ordinary piece (one that has metal in the areas that contribute least to strength).

Maybe an engineer can explain it better, but I think in the case of an I-beam, it's the same issue: placing the metal in the cross-section in such a way that puts it where it contributes most to strength.  In a large, long piece, you would have the added consideration that metals in any areas not optimal to the ideal design actually become more or less dead weight, weighing the span down while not adding much to it's ability to resist design stresses.

[red]PRK

What about the blood groove in the buttstock of the newer AK rifles?

stiffen the blade? fluted blade[:)]

From my understanding the "blood groove" is supposed to help releive suction. If the groove was not there and you stabbed "something" with blood in it. The suction of the blood and guts would hold the blade and it would be harder to get out. The groove is supposed to releive some of this suction by allowing blood & air to get in and out easily lowering the suction.

When I went through Basic training we were told that the blood grove on a bayonet was to help break suction. If we couldn't pull it out by bracing our foot on the BG then we were to fire a round off.
Ron