.308, You'll have ta read the manuals for each chrony you're interested in, I think the Master's memory is accessed thru a printer because it will do SD and averages with a printer hooked up. The Beta has instructions for clearing memory, the Master doesn't. Dunno for sure, I'm not interested in that feature, having to pack a printer to the range is more than I want to mess with, the chrony and tripod is bad enough.