>>2771836Depends on climate, weather and skill level. I've done with less than 5l (pockets on cargo pants and a canteen pouch on a sling) in autumn, knowing there were plenty of springs to refill my water, and with around 100l (pack volume - I compressed it to about 50l, iirc) in the height of summer, carrying 15 or so liters of water, a few changes of clothes and a full tent.
I'd look at how big the military standard backpack (not the assault pack, but the one used for guerilla / hunting type combat) in your country is and start with that. Since you won't be carrying ammo, and probably will have somewhat smaller gear, you probably won't need the entire volume, but you certainly won't need more.
>>2771899my proselytizing is bearing fruit, huh?
Some advice:
Leave the shoulder straps loose. If the waist belt is tight, all they do is stop the pack from tilting too far back. They're not meant to carry weight as on a frameless pack, though (on most packs) they can, if the waist belt should break.
Keep the space between frame and back free. Some people stick pads in there, but at that point, you might as wel use a internal frame. The main advantage of external frame vs. internal frame is that air gap, that let's your shirt dry somewhat and reduces rubbing and sore spots.
Don't strap stuff (machete, rifle etc) directly to one of the frame's sides. I know, retards who've enver gone out claim it works, but it'll cause stuff to flip inward and rub against your shoulder. For things like that, either strap to the pack (if you have loops like on an Alice / Molle) or tie a strap to the frame on both sides, pull it tight around the loaded pack, then strap to that.
