Yes, it is a force (or kinetic energy) measurment usually in Ft-lbs (in the english system). The physics equation is F-ma (force = mass times accelleration). It's easier to think of it as the weight of the projectile and how fast it is moving. lighter slugs will need to travel faster in order to deliver the same energy as a slower, heavier slug. Of course, the farther out the slug has to travel, the slower it will fly, thus a decrease in force or energy. Many sabot manufacturers will publish this info on the box or their web site, along with the velocity at various distances. For example, Hornady SST's in 20ga has a velocity of 1628 FPS and a force of 1471 Ft-lbs at 50 yards ... Remmington copper solids at the same range is 1360 FPS and 1187 Ft-lbs. It is sometimes suggested that 900 Ft-lbs is the minimum energy or force required for deer. Hope this helps.
