I then calculated various combinations of simulant (placed over primer) and N160 (placed on top of simulant and hence under bullet) for testing. In each test, I seated the Remington 405-grain JFP to an overall length (OAL) of about 2.56-inch, using an RCBS seating die, adjusted to provide a slight roll of case mouth. Since significant theoretical work by Byrom Smalley and myself on the SMc© patent had suggested that effective primer plume penetration depth was unlikely to exceed one-half inch, the first test used sufficient inert material to form a compressed simulant column about 0.9-inches long; when this failed to result in propellant ignition, I tested progressively shorter simulant columns until propellant ignition did occur.

Results of this test were a startling confirmation of every aspect of our theory – with typical rifle propellants, effective primer plume penetration will be about one-half inch; among large-diameter primers, primer choice makes very little difference in penetration depth (however, a "hotter" primer can generate effective ignition significantly further toward perimeter of case – although penetration depth is not significantly greater, more granules within the ignition depth are initially ignited); within normal typical bounds, percentage of propellant compression makes very little difference; granule packing scheme can have a modest influence. (Subsequent preliminary testing, suggests that plume from certain small-diameter primers, particularly Standard Pistol types, can demonstrate significantly less effective penetration.)