Briefly, our goal is to advance the state of the art in cartridge design by creating chamberings having the greatest performance potential. This is achieved through application of modern solid fuel rocket motor internal ballistics technology. This is unique to SMc™ designs.

Historically, cartridge design has generally been secondary to gun design. Chosen case configuration – cylindrical, tapered or bottlenecked – has been in direct response to desired energy level, (usually) availability of existing cases from which to create a new design, and (most importantly) fitment of any new design into a particular gun (whether a new or an existing design). Rarely has a gun been designed that requires creation of an entirely new cartridge. Typically, a new gun or gun chambering was designed and then a new cartridge was created – through modifications of an existing case type – to fit that gun.

Hence, most current and obsolete cartridge designs have resulted from alteration of an existing case – e.g., necking 308 Winchester (simply a shortened 30-06) down to 24-caliber to make the 243 Winchester. Such conversions are relatively easy. Making a new bunter (the tool that creates the headstamp) and the final forming tools required for such a conversion costs about $1000, circa 2000. Conversely, creating new tooling (as required to create an entirely new case design) now costs more than $20,000.

Hence, usually, when a "new" chambering is introduced, it is merely a necked (up or down) version of an existing case; more rarely, body taper or case body length are altered; very rarely a new design has a unique case head diameter (the 10m Auto is a recent example). Adopting a new case to an existing gun often requires significant alterations and sometimes an entirely new design.

Therefore, lacking a compelling reason to create a case with a different head diameter – such as fitting a specific gun design, or achieving improved ballistics – this approach to new case designs is simply too expensive. For these reasons, historically, other than as a result of pure coincidence, case configuration has been completely unrelated to internal ballistic efficiency. Enter the SMc era.

We concluded that in the ideal design, internal case diameter and bullet diameter would be linked; the correct relationship is near 2.1 to 1. Hence, other than by pure serendipity, ideal case designs cannot be based upon existing cases! Specifically, existing case diameters correctly match only a few standard bullet diameters for optimum efficiency.

Nearly ideal SMc designs in calibers 20, 22, 24, 25 and 26, and 28 can be achieved using existing cases – respectively, 6mm Norma BR, 284 Win or 45-70, 7mm SAUM or 300 WSM, 416 Rigby, and 505 Gibbs. The SMc 20-caliber conversion is a direct modification of the 6mm Norma BR case through resizing only. Forming the 22-caliber SMc from Winchester 45-70 cases is feasible through many necking steps with annealing and neck turning (to make it work in any standard bolt-action rifle, the case head must be re-cut to rimless configuration) – while the 284 case is of the correct diameter to make a 22-caliber SMc case, 284 case walls are far too thick. Forming the 24-caliber SMc requires case shortening and driving the 7mm SAUM case shoulder back significantly, which is feasible (this requires annealing) – we believe the WSM case might also be practical for this application. SMc designs in 26- and 28-caliber are impracticably difficult because it is necessary to redraw the case body to thin it sufficiently so that necking is possible.

Conventional receivers will handle SMc designs only up to 26-caliber. Several custom manufacturers make receivers that will handle SMc designs up to 30-caliber but these are relatively expensive (an SMc for 0.375" bullets could be adapted to 50 BMG receivers but, again, case conversion would be monumentally difficult). We are working toward correcting these limitations and at least one mainstream manufacturer has shown interest in introducing a larger action that would work with a 30-caliber SMc.

As discussed in the associated articles, we also recognized that shoulder design is important, as is neck length. We have designed all SMc cartridges accordingly with a specifically shaped elliptical shoulder and an unusually long case neck. The former contributes to ballistic efficiency; the latter contributes to long barrel life.

Handloaders should also be aware that in SMc cartridges the relative speed of propellants is not as might be expected. Generally, all propellants tend to burn faster than when used in conventional cartridges, the slower the propellant the greater the bias. Moreover, extruded (tubular) propellants seem to show a greater bias than do ball-type propellants.

Since we believed (and have since proven) that ideal case designs would provide sufficient ballistic advantages to warrant the effort we set out to create and test such designs. Parallel to this testing was our decision to patent this new art. Comparatively, the latter was a far more difficult decision. We certainly do not want to hamper state-of-the-art advancement but we recognized that our investment would be significant.

We now hold patents covering all aspects of SMc cartridge, chamber and tooling designs. Since these are parametric patents it is impossible to circumvent the concept by making minor dimensional changes.