Thank you for the info folks!
CT, the padding was the first thing that caught my mind as well. I have a family trip coming up and was trying to get a pack for misc. stuff and didn't need all the bells and whistles on this one, so I agree with you.
Sweeper, similar situation here - 4 barrels - and wasn't thrilled to carry any of them. I had been working on that issue and finally ended up with an old Kelty pack that can hold my smallest, then my 30 can go in an older Woods Mason pack.
For the big 60's I purchased a hunting pack frame from Cabela's that has no bag, but has a shelf on the bottom that flips up and down. I can put the barrel on the shelf and load all manner of crap on the frame. Just like carrying in external frame pack with padded hip belt and straps, which you have already figured out!