Karsten, I think I see where you are confused...
A flat shooting cartridge is one that propels its bullet at high velocity. The bullet will have a high ballistic coefficient (it has a streamlined shape) so that it does not lose its velocity rapidly due to the resistance offered by the air it is passing through.
An accurate cartridge is one that repeatedly places its bullet in the same spot, shot after shot.
A firearm does not have to be flat shooting to be accurate. It can have a rather rainbow-shaped trajectory and still hit where it is aimed because of the fact that it has been sighted in to hit (generally speaking) the point of aim at some predetermined range.
As an example, a .300 Wonderwhumper may sling its bullets at 4500 feet per second and have only 6 inches of drop at 400 yards when sighted in 1/2 inch high at 100 yards, but it may still be woefully inaccurate.
On the other hand, a .300 Whisper may push its bullet at only 1000 feet per second, and have 200 inches of drop at 400 yards when sighted in 2 inches high at 100 yards, and yet still be a tackdriver. It will have a "rainbow" trajectory, but we can still hit a bucket at 500 yards because it is an accurate round in an accurate rifle, and we can sight the rifle in to compensate for the trajectory.
You may or may not realize, but the typical high powered rifle has to be sighted in to shoot a little high (1-1/2 to 3") at 100 yards so that it will be dead on at some longer range, say 250 yards. The less flat-shooting a rifle is, the more the trajectory must be compensated for to be able to hold dead on and hit a distant target.
Take your .308 as an example. Shooting 165 grainers at say, 2750 feet per second, and you wanted to be able to hold dead on and hit a pie plate out to as far as possible, then you would have to sight in the rifle so that the top of the trajectory was no more than about 5 inches high. The top of the trajectory would be at around 150 to 175 yards or so. You would sight the rifle in to shoot about 2-1/2 inches high at 100 yards. As the bullet passes 100 yards, it is still rising to the top of its trajectory until it is reached (at about 175 yards or so), and then the bullet begins its downward fall. The bullet will then pass through the line of sight, somewhere beyond 200 yards. It continues to fall, and at some point is more than 5 inches lower than the line of sight. I would guess this range to be around 250 to 300 yards. As long as the pie plate was within 250 or 300 yards, you would be able to hold dead on and hit it. That is the "point-blank range" concept.
A flatter shooting round allows a longer point-blank range, and range estimation for hold-over becomes much less important.
I do not dislike a cartridge for not being flat-shooting, nor do I like a cartridge just for BEING flat-shooting. I have nothing against the .308, and I happen to admire the .223 and have two rifles in that caliber. I just happen to think that for all-around use, there are better choices than .308, and that's just my opinion. It's all subjective, and you are welcome to have your opinion too.
I hope you don't feel like I jumped all over you. Sometimes I am not very tactful, but I really do just want to help. I hope I have cleared this up for you.
-RR-
[Edited by RiverRider on 01-25-2001 at 10:02 AM]