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Range - Maximum level distance before the bb hits the ground. This value isn't terribly important or helpful, but might be seen as the theoretical limit for effective range.

Effective Range - Maximum range that a target can be effectively engaged.

Ex - Assume (made up numbers), that a DMR has a 60% chance to hit and has 5rps on semi, and a SR has a 85% hit at 1rps. Over one second the SR has an 85% chance to get one hit, while the DMR has (by my calculation), a 98.976% chance of getting at least one hit, which, to me, has a higher effective range. The DMR can go down to ~30% hit and come out with a 83% hit over one second, at 5rps.

IMO bolties were never meant to go head to head with a DMR, because odds are he'd lose every time. The strength of a bolt action is a high probability for a single hit in order to preserve "stealth". Normally on the field, I see people using BA's like they'd use any other gun, I.e. out in the open, moving with a squad, etc etc. Missing once is unlikely to arouse suspicion, but a few shots in rapid succession would. 

So, in summary, the goal of BA isn't meant to outrange your opponents necessarily, but to "outfieldcraft" them. That's my opinion anyway, but it's the only way it makes sense to me, otherwise "mobile" BA's would be pointless, as shown by my "statistic" above.

Accuracy - Grouping size from a benched or prone position. Will define as the largest distance between two hits of 11 shots (throwing out one flier), averaged over 3 sets on a sheet of A4 at 30m, 60, and 90m using Bioshot .32g(for now).

Pressure/Base Drag - Drag associated with the wake generated behind the projectile. 

Skin Friction Drag - Drag related to the surface area and roughness of an object.

Wave Drag - Drag produced when the object or parts of the object break the sound barrier, resulting in shockwaves

Ex - A thin plate perpendicular to the flow has very high pressure drag (and very little skin friction), but a thin plate parallel to the flow has very high skin friction drag (and nearly pressure drag).

Magnus Effect - Lift-producing mechanism in airsoft, which relates rotation, linear velocity and lifting force. The bb accelerates the flow over the top of the bb, and decelerates the flow underneath resulting in lift.

Backlash/slop - The amount of slack before useful motion is achieved after changing direction

Hopup Classification Scheme:

Level 0 - Hard Cylindrical/Flat Nub (Stock)
Level 0.5 - LRB
Level 1 - Hard Concave Nub (SCS)
Level 1.5 - Soft Concave Nub (R-Hop)
Level 2 - Soft Flat Nub (Flat Hop)

Note: The level is not indicative of the effectiveness of the hopup, but rather the "dimension" of contact i.e. 0, 1 and 2 correspond to a point, line, and area repectively. Because the deformation between a hard nub and a dynamically concave nub is so great, the hard nub can be approximated as incompressible (and of course ignoring bucking interaction for this classification). The R-hop is more compressible than a hard nub but less compressible than a soft flat nub, so it ended up with a Level 1.5

Concavity Definitions

Static (Formerly Active) Concavity - A surface of contact which can maintain its own shape. Yields a 1 dimensional area of contact along the top surface of the bb (Line) 

Dynamic (Formerly Passive) Concavity - A surface of contact of a compliant material which conforms to the bb as it passes by. Yields a 2 dimensional area of contact along the top surface of the bb (Area).

"Stock" Concavity (Convexity?) - This is generally seen in stock guns with the hard(ish) cylindrical nub. Yields 0 dimensional area of contact along the top surface of the bb (point). (Not terribly happy with the name for this one)

"LRB" Concavity - Similar to "Stock" concavity in contact area, but utilizes a long contact duration low torque interaction to impart the necessary spin along the top of the barrel. Tends to be more consistent than other impulsive methods of applying spin.(Not happy with this name either)

Contact Area - (Maximum) contact area with the bb at any given time

Effective Contact Area - Contact area integrated over time i.e. The LRB (ideally) has a point of contact, when integrated over the entire barrel, yields a line of contact. The static concave has a line of contact, and when integrated over the length of the barrel, yields an area of contact. A dynamic concave has a surface area of contact, and yields a "volume of contact".