Ive had a blacks creek pack barrel on me, but I couldn't get my old ku3700 to barrel. Not sure why, seems like the ku packs are built to barrel but mine never did. I agree with Luke in that I don't see how I could barrel my bikini. I havnt had the bikini out on the trail yet, but I did load it with gear & water in my high camp bag, & had no issues with the bladder poking through. I did have the bladder poke through when I removed the high camp & attached the new bladder sleeve & a hanging meat bag over it with a medium pod attached to the bottom of the frame. I tried the big zip & the dromedary 4 ltr. & got the same results with both. Like others, I found a paracord web or two of the horizontal lashing straps to be the cure.