Sheridan Model F's are my favourite CO2 rifle and are to be treasured -- they are rare here in the UK (and Europe) and I gather they are becoming harder to find in the USA.
I haven't had mine checked for a while but they were doing about 8/9ft lbs if I remember rightly. As you suspect Louis, they are gas guzzlers and shot count is quite low -- I usually get 20/25 usable shots per capsule.