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Some thoughts on rucking:
The following applies to the ALICE series of ruck sacks. I use an ALICE Large.
There is a stitch in the quick-release on your shoulder straps, cut that stitch so that the quick-release actually works like it is supposed to.
Route your cinch straps back up over the top of the ruck frame BEFORE you send them through the keepers on the ruck flap and then into the buckles. The stitching which holds your ruck together will last longer.
Stow those cinch straps in the empty space behind the outside pockets of your ruck. Don't be a slacker/leg/pogue looking like he doesn't know what he is doing in the field.
Load your ruck with the weight as high and centered as you can possibly make it. A man's center of gravity is in his chest and shoulders. That is where the weight should be.
I have always tied off/taped off the back pad on the ruck. I tighten it as much as I can then tape off the straps against the frame. It will get in the way when you have to drop ruck quickly. It is also "stuff" that you shouldn't worry about. Simplify things.
Keep the top of the shoulder straps tightened as close to the frame as you can wear them comfortably. If those straps are long the ruck will ride further down your back. See comment above.
Tape off all remaining loose ends. Don't be a slacker/leg/pogue.
Always use a waterproof bag inside your rucksack. Double layer it if you have two. If not, try a compactor bag inside your G.I. waterproof bag.
This is important! When training, do not carry large loads or heavy weights. It is important to train for mobility first. Put in 35 pounds to start. Again, make sure your load is high and centered. Work on your speed. Then increase your load in 10 pound increments. A sandbag fits nicely inside the radio pouch against the frame.. When you can comfortably road march 4 to 4.5 miles per hour with moderate weight, then start adding poundage. If you can move like a cat in the woods and a speed demon on the trail, you can wear any weight required. Condition yourself first.
Don't go for long distances when training/conditioning. Do 6-8 miles a couple of times a week. Again, work on your speed. Stretch that stride. Do a 12 or 15 miler once a month or so. This will help condition the mind. An all night 24 miler will only wear you out and get you to thinking you really don't want to do this. It may be necessary at some point, but not in the conditioning phase.
Remember, the mission dictates the load your carry. Actions on the objective will not require a 90 pound ruck, you'll ditch that before hand. When you do drop that heavy ruck and prepare for action, you'll feel like you're floating.