I want a rifle and cartridge that will shoot flat for 300 yards as a minimum. What is the best bullet, cartridge or rifle to use for this?

Mburu,

This is a great question. But you are kind of asking where you can find the holy grale. Shooting flat out to 300 yards can be achieve by virtually any cartridge that can produce over 3300 ftps if you use a bullet with a good Ballistic coeficient. But that answer is only yo let you punch holes through paper.

What animals are you planning on shooting? Do you have a budget? What type of bullets do you want to use? Are you planning on shooting at distances farther of closer than 300 yards? There are some open tip bullets with very high BC's that will do an amazing job on varmints up to coyote sized animals. But it you use this same bullet on a larger game animal, you could have very bad results.

Anyway, Let me give you a list of cartidges by caliber and you can decide for yourself. 17 Remington, 22-250, 6mm Rem, 270 WSM, 7mm Rem Ultra Mag, 300 Weatherby, 300 Rem Ultra, and 338 Rem Ultra. Make sure you pick the right bullet and the right BC. Muzzle velocity can fall of by 25% and 30% every 100 yards. So a real smoke wagon can be a sputtering puke at 300 yards with the wrong bullet.

Okay I gotcha,

I want a commonly available rifle and cartridge combination, and I don't want to have my shoulder knocked off when I shoot the rifle. So forget the Ultra mags. And I want to be able to shoot Antelope, Deer and Elk with the Same Rifle.

So If I do what you said, I would think a 300 Win Mag, a 7mm Mag, a 30-06, 284, 270, or even 264 Win Mag would do a good Job. I guess that makes sense if I use the right bullet in that cartridge. I guess I would lean more toward the 30-06, 284 or the 270.

You appear to want an all around rifle for everything, such an animal does not exist. The 30-06 comes closer than any other rifle. Your problem starts with which cartridge you use for different game. A 210 grain or bigger needs a different barrel twist than a lighter grain round. I have used an '06 for years to hunt elk, bear, hogs with a 210 grain bullet. . I use a .270 with a 165 Nosler Partition for deer, antelope, javalina and bobcats. I use a 243 for coyotes, prairie dogs and smaller varmints. If you want a flat shooter do not buy a short barrel rifle, get a 24" or 26" barrel. I just bought a 45-70 Quigley clone with a 32" barrel, it is a limited range rifle but I am going to use it for a grizzly hunt. The rifle is single shot but my hunting partner has a .375 for a back up.

I think an 06 or 270 is a great all around rifle/cartridge. However, I agree with TxCoyote. You will have better succes by paring the caliber size and bullet weight to the size of the animal you are shooting. If you buy a 270 or even a 270 WSM, you can shoot flat out to 300 yards, but you will blow the crap out of varmint sized animals and small deer. If you harvest anyting bear sized or larger, you will have to get a heavier constructed bullet to keep that high velocity slug from exploading on a heavy impact. So the problem you will have is under expansion and over penetration (Not what you want with bear, or wild boar). TxCoyote realy has the right idea. Bigger animals need bigger bullets. For smaller animals, go with smaller and faster bullets. Good luck man. But for anykind of deer and elk, a 30-06, 270, or 7mm mag are some of the most common, most proven and most versitile rifle/cartridge combination you can find.

MBURU in your initial question you said "... 300 yards at a minimum"
You are saying that you intend to shoot something from 300 yards to what 5000 yards?
The only weapon that can do that hasn't been invented yet but its name is a "Phaser"
And as the other guys have already answered very well, the only thing I can add is whatever you are going to hunt, you should get some professional training before you ever leave town.
Shooting anything comes with the caveat that you take ethical killing shots.
Good Luck!