It depends on the stamina of the person , as amigos says. They bag must weigh less in order to walk more. So try ignoring some things from your inventory, carry only the valid items.

In the army by back pack was between 75-100 lbs and one time it was 120 lbs........at that time my weight was of 125 lbs, I was one of the lightest guy in the SF at Bragg.

Now I weight 168 lbs and my back pack, all three of them, 35 lbs.......add the rest of the goodies and it would be about 52 lbs.

Remember that your back pack is only to get you to your next supply and not to last you for the rest of your life.

Always wear an extra belt, under your weeb gear, that will hold your pistol, knife, water and a very small pack..........this is in case you have to "drop" your back pack, rifle, ammo and all the rest and run like hell.

If you have to run like hell then leave a false tril leading forward and then backtrack to the point that you started from and then take them down one at the time, if they have dogs then find a creek and stay in it for about a mile and then backtrack........I also carry 3 oz of red pepper to put on my trail, this will drive the dogs crazy and they will loose their sence of smell.

Don't become the hunted but the hunter.

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"To be ready is not"... Ponce

"If you don't hold it, you don't own it"... Ponce

Try it out and see- the best way to find out is to hump it around for a few miles. Personally, I like mine as light as possible. The main weight with a BOB is water, everything else is more or less lightweight.

First: an external framed pack is better used on trail and an internal framed pack is better off trail.
The why is simple center of gravity, with both packs packed identically, the frame puts your pack
1 to 3 inches away of your back. This is great for ventalation but not so good for when you are
climbing over stuff.
second: a well built pack put the weight where it belongs, on your hips, These are the larger
bones and muscles in your body and they can take the strain much better than your shoulders
and back.
Third: As to weight, It really depends on what shape you are in

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Retired Navy SERE (Survival, Evasion, Resistance, Escape) Instructor
certified pistol, rifle, shotgun, home defense Instructor
NRA Life Member
Survival & Disaster Preparedness Instructor