Adjustable Objective
(AO) - In
scopes, the front objective turns to focus the image. Most AO
scopes also have yardage ticks to rangefind while focusing.
Airgun Rated (Scopes) - Can mean one of two things: 1)Built strong enough to
handle a heavy recoiling spring gun, which recoils both rearward
and forward, which is more harmful to scopes that high-power firearms.
or 2)Built to focus down to closer ranges than a typical firearm
scope, normally about 10 yards as a minimum.
BAR vs PSI (Air Pressure) - Two standards of measurement for pneumatic pressure.
1.0 BAR is equal to 14.5037738 PSI. So, 200 BAR x 14.5037738 is
equal to 2900.75 PSI. To convert PSI back to BAR, divide by 14.5037738.
Foot Pounds (Ft/Lbs) - A way to measure energy
based on the velocity and the weight of the ammunition used. To
calculate, use the following equation:
Gas Ram - Similar to a spring gun in
function, without the mainspring. A gas ram is a gas strut placed
in the compression chamber of the rifle. Behind the piston is
compressed air. When the airgun is cocked, the air is further
compressed. When the airgun is fired the air expands and pushes
the piston forward, compressing the air in front of the piston
and thus fires the pellet.
M.O.A. - Acronym for Minute
of Angle. Minute of Angle is defined as the distance of a line
that is made from point A to point B of an angle of one minute
of one degree at a distance of 100 yards. More simply stated,
Minute of Angle is movement of 1 inch at 100 yards. A scope with
1/4" MOA will shift 1/4" of movement at 100 yards for
every click of the turret. Target scopes have finer adjustments
with 1/8" MOA, allowing for 1/8" of movement per click
at 100 yards.
Moderator - A device designed to reduce muzzle report on an
airgun by moderating the air released when firing.
Parallax
- Dictionary says: An apparent change in the direction of an object,
caused by a change in observational position that provides a new
line of sight. Practical definition: Cross-hair picture moves
off target depending on head placement. Focusing the scope properly
can eliminate parallax and improve accuracy by eliminating the
error in head placement.
Precharged
- Any airgun that requires gas to be transfered to an onboard
tank to generate its power.
Pneumatic
- Any airgun that uses compressed gas as
its powerplant. Examples would be Precharged, Single-Stroke, and
Pump-up.
Regulator - Device that
steps the pressure in the air cylinder down to a lower level to
maintain consistent pressure for the airgun to fire from. Often
found on match grade rifles to ensure absolute consistency.
Single Stage Trigger - Typical American hunting trigger that breaks upon
application of pressure.
Target Turrets - Raised
adjuster knobs on a scope that can easily be turned by hand without
use of tools.
Two
Stage Trigger - Small amount of take
up is the first stage, coming to a complete stop. Second stage
breaks and releases trigger with any further pressure.
Underlever
- Any airgun where the cocking lever is seperate from the barrel
and located beneath the barrel. Most run parallel with the barrel,
but some are inside the stock.
Velocity
- The speed at which the ammunition is being propelled. Normally
calculated as Feet-Per-Second (fps).
