Which Is The Fastest Bullet In The World?

The fastest bullet in the world is the Winchester .223 Super Short Magnum. It has been known to reach speeds of  4000 feet per second which is the equivalent of 2,700 mph. This type of bullet is a rifle cartridge and was created by Winchester and Browning. The bullet was introduced in 2003 by the Browning Arms Company, Winchester Ammunition and Winchester Repeating Arms company. To this day is one of the fastest cartridges ever produced but not the fastest
The bullet is 5.7mm in diameter with a 6.9mm diameter neck and has an overall length of 60mm.
Before the bullet reached commercial production, there was controversy about the bullet as it was thought that the bullets would be hard on the gun barrels (or a barrel burner). However this comment was rejected by the maker, Browning.
Other bullets such as a .22 calibre bullet usually travels at about 400 m per second (1000 feet per second). A rifle bullet travels faster at rates closer to about 1000 m (1km) per second.  The speed the bullet leaves the barrel is determined by the gun and by how much gunpowder is pushed into the gun alongside other factors that determine how fast the bullet is shot out.

Go big or go home!  M1 abrams 120mm main gun fires with a muzzle velocity of 5510 fps (apfsds). Just thought I would add that tid bit.

I have hand loaded and shot .22cal 36 gr. Rounds through my Remington model 700. The maximum velocity I hit was 4503fps at the muzzle. This took a lot of tweaking on powder gr. And not to mention O.A.L. I'm sure there are faster, but this is the best I've done.

The wildcat 5 mm/35 SMc with a special 30 grain bullet and 28" barrel has exceeded speeds of 4800 fps.

I don't know where a lot of you are getting your information, Factory ammo, the fastest I have seen is Hornady's 22-250 Varminator which is at 4450fps, this does not mean it is the fastest but I know for factory ammo, it has to be in the top 3 if not the 1st place. Reloading, according to every Official website being Hornady, IMR, Hodgdon, Nosler, Barnes, etc, is the 22-250 loaded with Hodgdon Benchmark powder shoots a 35g Nos LF bullet at the rate of 4476 FPS with 62,600PSI Pressure.  Your 45ACP is not even close as its max velocity is 1126 FPS. British 303 is max 2966fps. I cannot find any valid data showing a wildcat 5mm which doesnt mean it can't fire that fast but as for reloading data, 4476fps is the fastest recorded according to all reloading data found at the previous sites.   You can validate it yourself or find the speed of your reloads here. data.hodgdon.com/cartridge_load.asp

The 22-250 with a 40 grain Hornady Varminator or Ruger 204  with a 32 grain Hornady V-Max round are about the fastest for *production* rounds in 4200-4400 fps range.  Some odd and custom loads can do a little better.  Trajectories are roughly equal, with the 204 being easier on the barrel for wear and less recoil.

Has anyone thought of thr Remington Accelerator Cartidge? Its a 30 06 casing with a 55.gr projectile traveling 4010 fps. Also research the fireball..17 centerfire.

The question would need to be more specific.  The answer would be different if the question was:   "What is the fastest bullet from mass produced ammo"   vs.  "What is the fastest bullet fired from a rife, those custom loaded included"

I think that the worlds fastest shooting gun would have to be my dads 22-250 the highest calibre in the .22 range, yesterday my dad and I went to a gun shop in perth where he had bought these red tipped sharp looking bullets, that were capable of 4350-4500 fps,although his other old bullets would of reached about 4000-4300 fps!

Stop smoking crack. A 303, even with a .22 cal bullet will not hit 5000fps. Yea, I'm sure you saw a 303 Brit match or exceed 5000, fps.

The 223 wssm is not a bullet,  it is a cartridge.  The bullet is the projectile.
So the question should probably be what is the fastest cartridge - not bullet.
You can shoot the identical bullet from several different cartridges of the same caliber and the bullets will all travel at different speeds depending on the cartridge.
As for the fastest, when the velocity exceeds 4000 fps it becomes a question of which is better and that depends on what you want the bullet to do. 
Faster does not equate to better in most cases.
This is my own humble opinion, and I am by no means an expert.

A lot of people are wrong because the 17 fireball is the fastest name production bullet out there

The bullet with credit for being fastest is the Winchester .223 Super Short Magnum; it's reached observed velocities of about 1220 m/sec, 4000 feet/second or 2,700 mph (4400 km/h). Read more.

The gun determines the speed of the bullet, and how much gunpowder goes into it, as well as atmospheric conditions, as much as the properties of the bullet itself, that determine speed.

A .22 calibre bullet typically travels about 400 m per second (1000 feet per second). A rifle bullet travels faster (larger calibre, more gun powder) travels more typically about 1000 m (1km) per second.

Bullet speed vary between 750 and 4000 feet per second, depending on the many factors.

The bullet with credit for being fastest is the Winchester .223 Super Short Magnum; it's reached observed velocities of about 1220 m/sec, 4000 feet/second or 2,700 mph (4400 km/h).   Read more.

The gun determines the speed of the bullet, and how much gunpowder goes into it, as well as atmospheric conditions, as much as the properties of the bullet itself, that determine speed.  

A .22 calibre bullet typically travels about 400 m per second (1000 feet per second). A rifle bullet travels faster (larger calibre, more gun powder) travels more typically about 1000 m (1km) per second.

Bullet speed vary between 750 and 4000 feet per second, depending on the many factors.

Actually the fastest bullet I have seen is a 303 british with100 grain bullet  with a blistering 5300 fps

The one that outpaces all the others when all fired at the ame moment