Trumpet Flash Hole Drill

Description

Flash Hole Uniforming Drill with a Trumpet Profile that Improves Supersonic Flow of Primer Gasses.

Fluid Dynamics demonstrates that when a gas is flowing in a pipe that has a diameter reduction, the shape of the diameter reduction has a strong impact on the pressure and velocity loss of that gas as it passes the constriction.  So when combustion gasses from a primer flow from the primer pocket, into the smaller diameter flash hole, there is a pressure loss which impacts how quickly and consistently the primer gasses ignite the powder.

Traditional flash holes at the base of a primer pocket are effectively a sharp edged transition with a loss constant K=0.5.  Rounding the entrance edge even a little bit drops that loss in half.  Rounding it a lot into a trumpet shape can reduce that loss by a factor of 10x.

ShootingSight is happy to introduce a flash hole uniforming drill that simultaneously cuts a trumpet shaped edge to the flash hole entrance.  The double ended drill has a 2mm tip on one end, and a 2.3mm tip on the other, for use in both small primer and large primer cases.