Testing Platform

Testing Equipment

Testing Procedure

Each new piston is first measured for hardness with the Barcol Impressor. 10 readings are taken from separate locations on the "face" of the piston, and the results are averaged. The metal teeth insert is then removed and measured, using 5 readings per insert in different locations, the results of which are averaged and recorded.

Each new piston is photographed, then installed in the mechbox, with generous amounts of Dupont Performance White Lithium Grease plus Teflon used to lube all moving parts. Dupont Teflon Silicon Lubricant is used to lubricate the cylinder and piston head O-ring to insure a proper air seal. After installation is complete, the fully charged 1700mah 9.6v battery is attached and the mechbox is checked for cycling problems. If no problems are present, the mechbox is installed into the M15A4RIS testing platform and tested for muzzle velocity and rate of fire.

Muzzle velocity is determined with the hop-up off, the muzzle leveled with the chrono, and muzzle distance to chrono fixed to 3 inches. 10 shots are measured with 0.20g Tokyo Marui BBs. The lowest and highest measured results are discarded, and the remaining eight averaged and recorded.

Rate of fire is determined by recording a full auto burst of atleast 10 cycles. A distinguishing feature is found in the recorded wave form for cycle peak, and the span between said feature is measured. for the last 8 cycles, and averaged.

Piston stress test is conducted by determining the length of time required for 1000 shots, as calculated from the rate of fire measurement for the piston. The piston is then cycled at 10 second intervals until 1000 cycles is reached, with approximately 30 seconds alloted in between for cool down. Cycles occur with the mechbox installed in the testing platform, barrel unobstructed, and no magazine.

At the conclusion of the stress test, the test piston is removed and examined for damage.