High efficiency condensor for C5 vette

[zz28zz]

Is it common for 12oz cans to be short on refrigerant? I've never heard of that.

On the other hand, I also feel that one can only deliver about 11 oz. from such cans into the system, from venting the hoses to some remaining inside the can.

I can see that happening with hose purging. It would be interesting to measure how much is left in the can once it's down to ~25 psi or so.
I'll be using a scale this time.