The 9.3x62 has been a standard chambering for Sako in Canada for 20 years the 9.3x66 for 2 years, I thought the 62 was available in the US but not the 66. Factory velocity for 286 gr is 200 fps higher for the .370 than a 62.Handloading you could gain 100 fps in the 62 by loading to the same pressure as the .370 but loading data above 2350 for the 62 is hard to find. There are no .35 Whelen loads close to .370 ballistics. The .370 pushes a 286 gr. bullet to the same velocity, 2550 fps,as a .375 H+H 300 gr., with the same SD but with about 15 gr. less powder and 2 shot more magazine capacity. Sako does offer more bullet weight combinations in the 66 than Federal does for the .370
