After 3 minutes of flying time (which is implausible, given gravity), the distance travelled by the bullet in a second is 8 centimeters less, entirely due to the effect of drag. Since theyвЂ™re so aerodynamic, the force of drag doesnвЂ™t have that much of an effect, but there is a measurable slowing. It turns out that bullets are pretty aerodynamic, which is probably no surprise. The effectiveness of the drag force is related to the density of the object youвЂ™re pushing through the air (which is reasonably low for a bullet, since the mass is so slight), the surface area of the object being pushed through the air (which also is small for a bullet), the aerodynamic shape of the object (a flat surface offers more resistance than an oval), and then the velocity of the object. If you take the initial horizontal speed of a bullet to be 300 meters per second (which is the metric equivalent of 1000 feet per second, and the math is much easier in metric), you can work out the rate at which the bullet is slowed down due to drag. We can actually calculate how long it would take for the forward motion of a bullet to be stopped completely by atmospheric drag. Anything moving through the air will encounter this force, so any bullets fired on the Earth will have their forward motions continuously slowed down by drag. We call this slowing force вЂњdragвЂќ or, less inventively, вЂњatmospheric resistanceвЂќ. The air around us resists the motion of anything moving through it, particularly at high speeds. The air around us seems pretty inconsequential, but if you try to move through it quickly enough, the air itself provides a very substantial resistance meteors encounter our atmosphere almost like a solid wall. On the ground, we also have gravity pulling the bullet rapidly to the ground, but we also have the atmosphere. In space, the only force that would act to slow down (or speed up) that bullet after being fired is gravity. For a pistol, this is somewhere around 1000 feet per second. So if the gun is the same and the bullets are the same, the вЂњmuzzle velocityвЂќ - the speed at which the bullet leaves the end of the gun, relative to the gun itself - should be identical in space and on the ground.

If you were to take a handgun, fire it on the Earth, and then take it into space (which is illegal, by the way), and fire it again, you would have kept everything that produces the speed of the bullet (the mechanism inside the firearm) exactly the same.

Speed of sound in space