TrapperJ,
No problem, I understand your concerns regarding zippers, I too have had equipment failures deep in the field and understand the consequences of a poor or untested design. The zipper we use is YKK #10 water resistant zipper with a crosswise breaking strength of 308 pounds as listed and tested per ASTM-D-2061. This zipper and size has been a standard in the USA made pack market for military/berry compliant packs and products and has a long positive performance history in the field. Many of these applications are on large volume, load carrying bag designs (primarily as a sleeping bag access zipper which bears more load per zipper inch than my vertical design.) While the strength of the #10 zipper is more than adequate for our design, the two front compression straps actually support a majority of the stress once tightened. I have been very thorough and meticulous in material selections and design, I can assure you the front zipper is not a weak link in the regards to strength or durability even under heavy load.
Thanks for your comments and let me know if there are any other questions I can help with. Merry Christmas!
Kurt
