Higher performance 20-caliber numbers have significant merit. Consider the 5/35 SMc™ (5mm-bore/35 grains usable case capacity – grains of water to base of neck). This cartridge utilizes patented case design technology – case diameter to bullet diameter ratio and shoulder design are chosen to provide maximum velocity with minimum barrel heating and wear. Superior design and case capacity advantage allow the 5/35 to achieve a significant velocity edge over the 204 Ruger – about 300-fps with any given bullet. Superior case design allows the 5/35 to achieve such performance without producing significantly more barrel heating than either the 223 or the 204 (see graph).
The 5/35 SMc is fully capable of delivering explosive velocity to targets out to about 400 yards and it will do so while generating much less felt recoil (sight picture disturbance) than will any 22-caliber or similar capability. In recent field testing, three shooters compared two almost identical guns (Savage Low Profile Varmint Models fitted with the Leupold VX-III, 8.5-25). One was a factory gun chambered in 223; the other was a factory Custom Shop gun chambered in 5/35. All three shooters agreed that, with best handloads, it was possible to see impacts on closer targets when shooting the 5/35 SMc, despite the significant ballistic advantage. Similarly, when the shooting was good, the 5/35 did not heat the barrel any faster than did the 223. Subsequent barrel heating studies carried out with the help of Savage Arms proved this to be the case – with best loads, barrel heating in the 223, 204 and 5/35 is similar (see graph).