Applying the most basic arithmetic, you can have a decent estimates if you have the ballistic coefficients and the muzzle velocity for the projectiles.

A standard 660 grain bullet fired by a M107 .50 Caliber Long Range Sniper Rifle has a muzzle velocity at 2,800 fps (853 mps) with a maximum effective range at 2,000 yd (1,829 m).

Assuming all things being constant (as the bullet can be affected by a number of factors such as wind, temperature, pressure, etc.):

## 5280 (feet in a mile) divided by 2800 (feet per second) equals 1.8857 seconds (at least).

To be more accurate, an on-line ballistics calculator will tell you pretty much everything. Below are some of the good calculators you'll find online:

## Hornady Ballistics Calculator

## JBM Ballistics Calculator

## Handloads.com Ballistics Calculator