Fuctional Comparison: MSP, ACP, & PCP

[DavidS]

As the questions an opinions seem to come up often, here is a look.    Constructive feedback welcome and encouraged.

First for those that do not know the definitions.
MSP: Multi Stroke Pneumatic (think Crosman 1377, or Daisy 880).
ACP: Air Conserving Pumper.   This is an MSP that stores enough high pressure air for more than one shot.
PCP: Pre-Charged Pneumatic.  Uses stored high pressure air in a tank on the gun, usualy needs to be recharged from an external source (Pump/tank).

With an MSP you use an built in pump to build pressure in a small air chamber.   When you fire all of the pressure is released to push the pellet.    In some cases the valve remains open, in others the valve is opened by a striker long enough to release all of the air into the barrel behind the pellet.

With an ACP you use a built in pump, just like the MSP, to build pressure in a small Air Chamber (usually a bit larger than the one in MSP's).   When you fire enough high pressure air is released to push the pellet, then the valve closes in time to retain the rest of the pressure, so you get more shots.  These almost universally use an inertial striker to open the valve for each shot.

With an PCP you fill a large air tank on the gun from an external source, up to the needed pressure.   When you fire the same thing happens as with an ACP.    PCP's usually take hundreds or even thousands of strokes of an external pump to charge to pressure, these may be provided by a hand pump, or a high pressure motorized compressor (such as used to fill scuba tanks).   Thus PCP's are basicaly ACP's with a larger air chamber for more shots, and the pump separated from the gun.

This is just a quick functional comparison of three nearly identical in function AirGun power plant types.

[DavidS]

One note left out.
Some of the PCP's separate the air tank from the shot air chamber by a pressure regulator in order to provide more consistent shots.     Though this is sometimes done with ACP's as well.

With pumpers the consistency is more about the person pumping, and maybe some slight tuning, thus no extra cost.