Are there any advice points on bottom film loading. As I don't home process now since E6 home kits went away,with the cost of film and lab processing messing up a film at the loading stage would be a concern.
Here's my process; first, obtain film:
Pull out enough from the canister that I can comfortably fit the width of my hand on it:
Freehand cut a half-thickness leader that then curves up smoothly and exits between sprocket holes:
It's really no more complicated than that, and should only take ten seconds, max. As long it's long enough and there's no hesitation marks or tearing in the new leader - and you don't come out through a sprocket hole - you can't really go wrong.
Once you get to the loading point, the crucial bit is to make sure the sprocket holes have engaged with the teeth in the film advance mechanism:
It's more awkward to photograph than it is to see!
Some of my bottom-loaders have a bit of a dodgy take-up spool that doesn't seem to align the film very well with the sprockets at first; usually rewinding the slack film in the canister to pull the film taut is enough to make the sprocket holes locate correctly. It's rare it takes me more than a couple of seconds to reload a Barnack now. People baulk at how "difficult" the process is, but I find it much more reliable and foolproof than most "easy" mechanisms for loading cameras. You've just got to know how to do it properly.
The only real thing that
can complicate things is that very early bottom loaders (pre-war Leicas, some early Leica IIIfs, presumably pre-war FEDs) don't hold the film in the correct position so you end up with the sprocket holes impeding on the image area. The solution for that (short of using a later bottom-loader) is to either use the correct cassettes or shim the baseplate. I doubt you're going to run into this problem with any Canon or any of the later Soviet cameras, though.