C.O.L. : abbreviation for Cartridge Overall Length, important to know to insure the loaded cartridge will fit in the magazine of any magazine feed rifle. This information is particularly important for the 338Lapua Magnum cartridge because SAAMI and CIP specifications for length are different and some rifle manufacturers offer magazines that allow even longer cartridges than are specified by the standards bodies.
FFP : First Focal Plane: A scope sight with the aiming reticle in the first focal plane so the size of the reticle changes as the magnification of the scope is adjusted. With old wire reticles often the reticle was too big at top magnification and would cover the target. Modern scopes with the reticle etched on the glass allow floating elements and skeletonized lines or bars that can work well at both low and high magnification. The main reason to use a reticle in the first focal plane is to allow accurate range estimation at any magnification.
MOA : Minute of Angle, approximately 1” at 100 yards or 10” at 1000 yards, one 1/60th of a degree.
Mil or Mrad : Milliradian, 1/1000th of a radian, an angle that subtends 1 yard at 1000 yards range. 1 mil ≈ 3.43774677078493 MOA for more see http://en.wikipedia.org/wiki/Angular_mil
Mil/Mil : A scope that has both reticle and click adjustments graduated in mils
1 : cast as a single piece
2 : formed or composed of material without joints or seams
3 : constituting a massive undifferentiated and often rigid whole.
1: an organized whole that acts as a single unified powerful or influential force
2: a single great stone often in the form of an obelisk or column
SD or S.D.: is Standard deviation a number that represents how much velocity varies from shot to shot.
BC also B.C. : Abbreviation for ballistic coefficient, a number that represents the aerodynamic efficiency of a projectile compared to a reference projectile. A higher number means the bullet will lose velocity slower and be affected less by wind as it travels down range.
Action: Is the physical mechanism that manipulates cartridges and/or seals the breech. Actions are generally categorized by the type of mechanism used. Example: Bolt Action, lever action, pump action. For more information see http://en.wikipedia.org/wiki/Firearm_action
Short Action: a bolt action rifle action designed to use cartridges with a maximum overall length of 2.800 inch. Example 308 Win, often considered more accurate than longer actions because the shorter action is stiffer all else being equal.
Long Action: A bolt action rifle action designed to use cartridges with a maximum overall length of 3.200 inch Example 30-06 or 300 Win Mag
Magnum Action: A bolt action rifle action designed to use cartridges with a maximum overall length of 3.600 inch. Example 375 H&H Magnum, 300 RUM. Some cartridges like the 338 Lapua Mag and 408 Cheytac require even longer actions.
Win: Short for Winchester often used in cartridge names
Rem: Short for Remington often used in cartridge names
WSSM: Winchester Super Short Magnum
WSM: Winchester Short Magnum
RUM: Remington Ultra Magnum
SARUM: Short Action Remington Ultra Magnum
WSM: Winchester Short Magnum
SnipeTac: A family of cartridges based on the 408 Chey Tac case necked to a different bullet diameter and reduced body taper.
Maximum Point Blank Range (MPBR): the distance between a rifle and a target 6 inches in diameter such that the bullet in flight is expected to hit the target without adjusting the elevation of the firearm. A 6 inch target is a common size for the vital zone on big game animals.
Hydrostatic Shock: An effect of high speed bullets that cause remote wounding and incapacitation via hydraulic effects in water based tissue. See http://en.wikipedia.org/wiki/Hydrostatic_shock