Good advice about the tape, I will have to try that. My first couple of rolls bulk loading this summer, I had two instances of premature detachment while on vacation. First happened on the ferry over to Alcatraz. Couldn't use the 35mm the rest of the night. Second was a couple days later wandering SF. I ended up sitting on the floor in the Starbucks bathroom, lights out, with our jackets stuffed under the door, so I could open the cam and roll the film back into the canister. Definitely learned my lesson that trip about being more cautious with my taping.
On the OP, I always pop my canisters open, either with a bottle opener for pre-rolled film or just pop open or unscrew my bulks.