New to shooting or an old hand, there is quite a bit of jargon to get your head around that is bandied about by shooters and idiots with shooting blogs online..... what... me???
Hopefully this glossary will help translate a few terms commonly used. In no particular order:
BULLET: A bullet. In our case usually a swaged piece of lead encased in a copper jacket so that it can be propelled at higher velocity than a pure lead or unjacketed bullet.
PROJECTILE: A bullet (or other object) that is in flight with the intent of causing impact at range. A bullet not in flight is a bullet, not a projectile. A bullet in flight is both a bullet AND a projectile
CARTRIDGE CASE: Commonly brass case that is formed to the shape of a cartridge chamber for the purpose of containing gun powder and bullet and primer in order to create a complete piece of ammunition, a round, or a cartridge.
P.O.A.: Point of Aim. Where you are trying to hit with your bullet.
P.O.I: Point of Impact. Where you actually hit with your bullet.
M.O.A.: Minute of Angle. An angular measurement approximately equal to ONE INCH over 100 YARDS. So, at 300yd, 1 MOA is around 3inches, at 500yd, it is 5inches, and so on. Rifle scopes generally have the elevation and windage adjustments set in 0.25MOA increments. Hence, one 'click' will be 1/4" at 100yd or 1" at 400yd.
Rifle optics are also made with adjustment turrets set at 1/8th MOA or in various increments of MilRad...
MilRad: Milradian. An angular measurement equal to 10cm (100mm) at 100 METERS. Rifle scopes will often have adjustments set in 0.1milrad. Milrad and MOA do not play nicely together. Pick one system for your optics and shooting and stick to it.
N.P.O.A.: Natural Point of Aim. When your rifle is pointing effortlessly at the bullseye. A natural point of aim is important in any kind of precision shooting. Your shooting position is what builds your NPOA. it is commonly said that you should be able to close your eyes and when they are opened your sights will be on the bullseye. If you have to re-adjust yourself or your rifle to get back on bull, you have not achieved your NPOA. A good NPOA is what allows the bullet to be released cleanly without torquing or influence from poor positioning during it's internal ballistics phase of delivery.
Internal Ballistics: What happens to the bullet between when the primer is detonated and the bullet leaves the barrel.
External Ballistics: What happens to the bullet between leaving the barrel and striking the target.
Terminal Ballistics: What happens when the bullet impacts the target.