There's two questions here: how many rounds through the gun to establish it's "boom reliability", and how many of a given load to make sure that ROUND works?
Through the gun, a couple of hundred rounds (of any/all types) is a good idea to make sure it's OK. I would recommend at least 50 of those involve CCI primers (Speer/CCI/Blazer brands) as those are a hit harder - if the gun can set those off, you're good to go.
In terms of carry loads, it can be as few as a couple cylinders full, to make sure you know where they print.