Understanding Projectile Spread and Shell Imbalance

Question
What is spread of the projectile?
what is effect of unbalance of the shells ? How to reduce the unbalance?

Answer
Spread can be the pattern that the bullet or projectile move or vary at difference distances.  The spread of a shotgun round is how much area it will cover at various distances.  Let's say you a double 00 buck shell, it has 6 .32 caliber round bullets.  At 5 feet they may spread only a few inches and you will all 6 rounds in a 4 inch circle but at 20 feet you may get all 6 round in a 5 feet circle, so the more it travels the bigger the spread gets and accuracy goes down.

If you are talking a single shot like a rifle or pistol, then the more accurate a bullet is depends on many factors.  But spread would be like if a gun was put in a non-movable vice and you fired 6 or 10 rounds of the same ammo and the same distance, under the same conditions (wind, weather, etc) then all 10 bullets would not hit in the same hole, there would a little movement with each bullet, so if all 10 rounds hit a within a circle of one inch, then that bullet in that gun would be said to have a spread of inch, at the distance the test was done.

Rick