I might as well follow up since this thread re-appeared, I noticed I commented almost 2 years ago!
The BV-500 in the 3400 worked fine either strapped up top or vertically with soft stuff packed around it, 200-some miles required on the pct. Â I had it up top while I had a lot of food inside (used bear lockers to extend the range of the canister). Once it would fit inside, vertically was fine. Â If you put that day’s food in a gallon zip in a handy spot the canister just stays inside.
I basically always pack this order, the bottom three things stay in all day.
lunch and snacks (on top or on outside).
Outer clothing
bear can (or food bag) with down jacket around it
bulky stuff: pot, bowl, ditty bag
quilt in stuff sack
Ground sheet + tarp (if its not wet), sleep clothes, bug net, all mashed in and compressed.
Except for more supple shoulder straps (like MLD) I have zero complaints about the HMG 3400 pack.
I saw lots of people having to creatively pack to get this thing inside their pack. Â I just put it where my food bag normally rides and it sat on the solid base of camp items.