Based upon this, I made the argument that the 20-caliber was worth pursuing. My basic belief was that if it was possible to make good 22-caliber barrels then making good 20-caliber barrels should not be a problem and that fouling should be only marginally worse in the 20-caliber. With newer and cleaner propellants and with moly-plated bullets useful 20-caliber chamberings seemed to be feasible.

Two critical factors drove this project to reality. First, the readily available 6mm Norma BR, an existing commercial case that was essentially ideal for conversion to 5mm with the SMc design. Second, other wildcatting and commercial developments were driving the availability of 20-caliber bullets. A third factor is no small matter, that conversion of Norma made 6mm Norma BR cases is so easy that anyone can do it in one or two steps! (due to different annealing, Lapua cases are not so easy to convert). (With our previous experiences in converting cases into 22-caliber, 6mm, 6.5mm and 30-caliber being akin to pure torture, we were both anxious for any conversion that was just simply simple! – the 5mm/35 SMc fulfilled that dream.)

Summer of 2004, on our way to and from the Varmint Hunter's Jamboree, Smalley and I, sported three 5mm chambered rifles, two in 5mm/35 SMc guns and one in the intellectual predecessor of those, the 5mm VarmintMaster (same basic design excepting a hemispherical shoulder rather than an elliptical shoulder with significantly greater usable capacity but a shorter neck, which likely significantly reduces barrel life). While varminting on that trip, we shot the 30-grain Berger LTB, loaded to about 4600 fps; the 32-grain and 33-grain Hornady V-Max, loaded to about 4500 fps; and the 40-grain Hornady V-Max, loaded to about 4200 fps in these guns. We fired around 700 rounds and we