If it hits nothing, it will keep going, and going, and going... But if you fire it on Earth, inside the atmosphere it will hit something. Usually the ground. The distance it travels between leaving the muzzle and hitting the ground (or water or...) depends on where you are when you shoot it and which direction you aim it. (If you point straight down, it goes about a foot. If you point straight up and there is no wind, it may land a foot from the starting point again.) For maximum distance, start at the highest altitude possible with the steepest drop-off. A 1000m high cliff would be good. Out the open door of an airplane at 10,000m would be even better. Fire the gun at about 45 degrees up from horizontal and your bullet will travel many miles. Even further if you fire in the same direction the airplane is travelling. Without providing additional constraints, the answer is between one foot and many miles. Actually, forever if fired in intergalactic space in a direction unlikely to bring it close to the gravity well of..... anyway... Any bullet fired horizontally out of a gun at sea-level over a horizontal field will only travel a few hundred meters (if that) before falling to the ground unless you compensate for distance by pointing the barrel up a little. Good gun sights provide tools for determining how much to angle up.

The answer to you question depends on several factors, most important of which is what do you mean when you say standard military rifle? There is no such thing as each country typically has its own type of weapon as the standard issue arm. If you mean the standard issue weapon, the answer to that question depends on the maximum effective range of the weapon involved. When the term maximum effective range is used, that term refers to the probability that an individual firing at a target at that specific range has a 50-50 chance of hitting the target. Why? Because no fired projectile, be it from a mortar, howitzer, cannon, tank gun, small arms (rifles, assault weapons, side arms, machine guns under .50calibers or 12.7mm) fires in a straight line. The projectile from a rifle travels in a somewhat flat arc from the point you're firing itand the maximum effective range is the point where the path of the arc meets the imaginary plane of the horizon. For this I'm assuming that you're firing horizontally to the ground So for example, if I have a rifle and its maximum effective range is 500 meters, that means that the arc the bullet takes begins to break the plain of my aiming horizon 500 meters away and begins to fall off. As a rule of thumb I was taught when I did gunnery exercises to use 2.5 of the maximum effective range for the maximum range. Alot of this also depends on the power of the propellent in the bullet. There'a really good example of this in the book "THE WAY THINGS WORK" or "FIREAMS" which is in the reference section of any library. If you can come by it, TM 9-2350-253-10 Tnk CBT FT M60A3 TTS Ch9 has a small section that deals with the ballistic capabilities of the both the coax and cupola MG's as well as the M-16.

a flat shooting 223 bullit will travel 800-1000 with out hitting any thing and at that range it is stiil deadly,

how far can a handgun bullet travel?

first it depends on the gun your using. the standered ar15 has a max range of appx 5550 meters but with a max efftive range of appx 450-550 meters

if fired with the barrel 45 degrees above horizontal, most rifle bullets will travel 2000-6000 yards. if fired level, horizontally, most bullets will hit the ground within 450 yards.

a .22 lr states 1 1/4 miles on the box, i'm not sure that is accurate but gives plenty of leeway for safety. i read somewhere ( sorry i can't site the source) a 140 grain .270 grain will travel up to 3 miles at sea level, the same bullet would obviously travel farther starting out at say 10,000 feet because of less drag due to thinner air at the elevation. but in my opinion the only way the 50 cal gun as stated above would go 50 miles is if you dropped it from 50 miles.

A 7.62 NATO round fired at optimum tragectory will travel about 4 miles. +5

I hunt with a slug!