I bought a couple of these from this guy recently. Been loading them up with 60 lbs to train and they seem to handle up to that weight fairly comfortably. Good product not from one of the major manufacturers, seems like about 1/3rd of similar name brand alternatives. I am liking mine so far, hope I get to use it in a month!
http://www.ebay.com/itm/Meat-Pack-Frame-handmade-meat-cargo-sling-/150639306013?pt=LH_DefaultDomain_0&hash=item2312cd651d
http://www.ebay.com/itm/Meat-Pack-Frame-handmade-meat-cargo-sling-/150639306013?pt=LH_DefaultDomain_0&hash=item2312cd651d