KenH did not mention a caliber, and so I would like to piggyback on his question. Does the bottleneck 45-75 brass have a thinner neck than the straight wall calibers, similar to the '73 dash-calibers being thinner than straight wall pistol brass, and therefore seal the chamber better? Or do the straight wall (or taper) cartridges all seal fine because they are more powerful than pistol calibers?
Abilene
my 45/75 brass made from 348 cases is thicker (+ 5 thou) in the neck than 45/70
Loaded 45/75 round measures .485 neck OD and is a NEAT fit in my Uberti chamber - to the extent I made an outside swage die and run all my loaded rounds through that to iron out any little crinkles so they chamber easily (little bulges from crimping etc)
My rifle shoots clean brass but there is no spare room at the front end of that chamber at all - the neck dimensions of the case chamber combo is as close to zero tolerance as you could get and still function
I clean much the same as Dusty - rifle upside down - I made a cradle for that and I use a flush bottle with a short length of plastic tube that goes in the chamber and pour water through the barrel first then one stroke with a brush or wet patch, another flush, another brush, etc, usually the third flush will run clean and the following patch will be clean - dry it with a few patches - I follow up with WD40