The .45 caliber bullet is not used in a sniper rifle.
The L1A1 SLR used by the British military is in caliber 7.62 NATO, and has a muzzle velocity of about 2800 fps.
Some of the fastest- the Ruger .204, the .220 Swift, and the 30-06- but only if the 30-06 is shooting the Remington Accelerator. That is a sabot cartridge that fires a small .25 caliber bullet at roughly 4,500 fps.
The muzzle velocity of a .270 caliber rifle can vary depending on the specific ammunition being used. On average, a .270 Winchester round can have a muzzle velocity of around 3,000-3,200 feet per second. It's always best to check the specific manufacturer's data for the most accurate information.
No one answer. There are dozens of different .44 caliber cartridges, and hundreds of different loadings of those cartridges. A rifle will have a different velocity than a handgun. This is sort of like "how fast can a V8 car go?"
muzzle velocity
300m/s
The velocity of a .223 caliber projectile can vary depending on factors such as the specific load, barrel length, and type of firearm. Generally, the velocity can range from around 2,700 to 3,300 feet per second.
Among standard rifle cartridges the Winchester .220 Swift is the velocity standard bearer. It clocks in at 4,000 ft/s (1,200 m/s). Rifles chambered in the caliber tend to have shorter-than-usual barrel lives. Among standard pistol cartridges the Smith and Wesson .460 is the current record holder at 2330 ft/s.
The M4A1 version of the M16 rifle has a muzzle velocity of about 2900 feet per second, firing the 5.56mm cartridge.
Muzzle velocity of the SS-109 cartridge is about 3100 feet per second.
Varies with barrel and cartridge, but the muzzle velocity is about 2600 feet per second.