First, there seems to be a lot of confusion about how to assemble this once you receive it.
You'll get one piece that is larger than the others. It has velcro on all four sides. This piece works as the divider.
Between the bottom and top zippered areas, you will find velcro on all 4 sides inside the backpack. The velcro is both sides of velcro stuck together. Separate one section so that the velcro is separated. My suggestion is to start in the back. The flap on the divider piece should bend downward. The velcro from the flap will attach to the velcro that was just exposed by separating the velcro inside the bag. Once that is connected well, the other piece of the velcro that was separated then covers the velcro on the backside of the flap you just connected. So, you'll have backpack, velcro, flap, and velcro again. Next, attach the front flap the same way, then the sides. Now, you have the divider/shelf in place.

If yours doesn't come with a loose board (mine didn't), take one of the divider pieces and place it in the bottom of the backpack. There is a pocket for it to sit in. This makes the bottom of the backpack rigid. I'm sure a piece of 1/4" plywood or luan or whatever could also be cut to go here if you prefer.

Next, take the other dividers and place vertical between the bottom of the backpack and the shelf/divider.

To give an idea of the size, the bottom could hold 5 boxes of 9mm (50 pack) of ammo on each side (stacked), with three pistols and dividers in place. The top could easily hold 20 more boxes of ammo.

One reviewer said that a grenade won't fit in the top side pocket. I don't have a grenade handy to check, but I think it would fit fine.

Pros: Everything is padded, making every wall thicker. The backpack seems very solid. Also, my 12 round double-stack 9mm mags fit perfectly, with room to spare. While a 30 round glock mag isn't going to fit in the mag holders, I think the review complaining about the size was incorrect. It should hold any full-size mags for handguns. An AR-15 pistol isn't a "handgun". Sorry.

Cons: Note that I only deducted one star, so some of this is more personal preference.
1. The divider/shelf is a very tight fit, which means that it pushes into the back of the backpack and therefore I'd expect could cause some spine pain if used for a long period.
2. The dividers and shelves are rigid, but I would prefer a real "box" for the bottom section. I don't think that there would be any issues of collapse, but a pre-made box just seems like a better solution. Obviously, it wouldn't ship in as small of a package that way, which is probably why it was designed the way it was.
3. No instructions. Sure, you can figure it out, but there should be some instructions.
4. No molle strips to add a small external first aid kit, etc.
5. I'm a big guy (that means FAT). The sternum strap isn't going to close on me and be comfortable. However, without the sternum strap, it also isn't going to fall off my shoulders either.
6. You can disconnect the shoulder straps and hide them in the zippered pocket, but you still have pieces hanging loose outside. Using rings and clips would have been better so you could just un-clip the bottom of the straps and tuck them away. However, my use for the bag was strictly as a backpack anyway.

Excellent product. What a great concept or range bag that is also a backpack. This is the first and only one I have seen designed like this and it is an excellent idea. Also like the fact there are many smaller compartments where many range bags and backpacks have a lesser number of large compartments were small items seem to disappear into the bottom. Very well constructed with heavy-duty materials. Only downfall is it did not come with any instructions on how to assemble and organize all the various dividers internally. It took a little bit to figure out how to set it up but again this is an excellent product.

Well made and great for keeping things organized. Excellent price! It has many features to make this bag comfortable on your back and an optional hydration pack. The only con that I see so far are no MOLE straps, a bit heavy, and it does not appear to be waterproof or resistant. I will be spraying it with Scotchguard. Oh yeah... The rigid construction does make it stick out a bit while it's on your back and makes it looks big, but your are basically carrying a locker on your back!

Extremely heavy duty and durable bag. Pockets are great and it holds a lot of gear. Ruger .22 pistol will only fit in one side pocket due to length of barrel. Would ask that assembly video play slower as item/box didn't include written assembly instructions and was challenging to figure out with video rolling so quickly what was the suggested installation. On that note, I would have gladly paid an extra $10 to have had it already assembled. The shipping box was big enough and the velcro is so secure - it was a bit of a workout to put together and difficult to see details well in a black bag!

hated it at first, but after some organizing and purchase of

https://www.amazon.com/gp/product/B00D79V78U/ref=oh_aui_detailpage_o00_s02?ie=UTF8&psc=1

now in love with it, i have 600 rounds in there, 4 guns, earmuffs, sides are slammed with mags and this bag is high quality, it could easily hold a couple thousand rounds if you really wanted to, will attach pic