1000m
The M16 is an assault rifle that is a .223 caliber / 5.56 mm. like any weapon it is only as accurate as its shooter, <><><> It can be very accurate.
Provde the caliber.
No You could build a rifle in .306" or any other caliber but you are likely referring to 30.06. A 30.06 rifle is referred to as "30 Caliber" but to be accurate it is nominally .308"
In all likelhood, one of the bolt action pistols in a rifle caliber, such as 6mm. That holds the accuracy record for a rifle, and would likely do so for a pistol.
In excess of a mile.
200 yards
900 meters, depending on the rifle, sights, and skill of the user.
Depends on the load and range.
About 300 meters, depending on the rifle, sights, ammo, and skill of the shooter.
Your rifle is a Marlin Model 81. Value could range from $50-$145, depending on condition. Most are around $100 or so. Accurate reliable hunting grade rifle.
If you mean a rifle chambered for the .50 BMG cartridge, such as the Barrett M82, the EFFECTIVE range is about 5,900 feet. The rifle weighs about 30 pounds, and sells for about $9,000.
You will have to provide the caliber and whether it is pump or CO2 powered.