We fired the piston twice, each with a total of .4 g of black powder. In both tests, the drogue successfully deployed.
During the set-up for the first test, we found that a certain clocking of the MP tube and the coupler led to the piston being misaligned with the cup and diaphragm.
In the second test, the Forward Retention Ring struck the MP tube after detonation of the firebolts. After the test, we say that there was bolt shear-out on the cup. This could have been caused by the FRR hitting the MP tube. We also noted that the piston bolts were loose during de-integration. Perhaps they had not been tightened with a hex wrench, which could have also contributed to bolt shear-out.