I'm going to say you should probably get about 140-160 shots of of the 13ci/3000 tank. That's if you don't waste a bunch at the chrony first. You could probably gain a bit by using a tight bore and running your velocity a bit on the low side......say 270ish.
This is based on the numbers others have posted here.
ETEK 3LT, with 14" critical .680 barrel and cure 3 + bolt F/S
DM12 red with matching Boomy F/s