Long guns have three points of support
: the butt of the stock against the shoulder, the shooting hand at the grip, and the support hand on the forearm.
AirLoc PAD-PAK Vibration Control Pads are pre-engineered and prepackaged to provide the proper leveling and loading for machines having four points of support
. Offered in 45 Durometer neoprene for low frequency applications and 70 Durometer nitrile to provide high damping, each vibration control pad set contains four base pads and four shim leveling pads.
Here, points of support
have been substantially reduced in scale and moved inward, and corners infilled with butt-jointed glass.
There should have been only three points of support in the original frame.
There are two consequences of the over-constraint that the four points of support represent: 1) The isolation bushings were designed for a low natural frequency (less than 10 Hz) and had a spring rate of 7.41 kg/mm (415 lb/in.).
Three points of support imply that the single bushing at one end would have seen greater load than each of two partners at the opposite end.
The linear unit requires only two mechanical points of support
per machine and/or magazine--i.e., no more than six points of support