The weak point on sewn goods is always the plastic hardware. The breaking strength of Cordura, webbing, even the stitching itself is many times stronger than any buckle, loop, etc. made out of plastic, even if it is a higher quality example like acetal.
I’ve personally tried to destroy buckles, hung some up in my workshop with weights hung from them, etc. I’ve been pleasantly surprised by the fact that the two 2" buckles on the Messenge’mups that suspend the bag from the shoulder strap have held up fine. They often have a good chunk of weight hanging from them, and my worry that they would break have not been borne out.
One type of buckle I’ve been curious how much it could withstand is the Siamese SlikClip. It was proven on Friday night. Trying to fold my freakishly long frame into a Mazda 3, the back edge of the NyfFyrLyt on my belt caught on the door frame. I wasn’t even so aware of it until I heard the sound of plastic snapping. I couldn’t tell you exactly how much force was applied. I’m sure it’s a complicated formula. 250 pound guy, metal car, the strength of the belt I had on, the strength of the webbing the buckles were attached to. But in practical terms, it wasn’t that much force.
Now in some ways it’s good that plastic buckles break fairly easily. My general outlook is that when there are instances where the plastic does break,
something really kooky is happening, and I want it to break, because I
am hung up on something, being dragged, etc. And yet there is also the aspect that I would like it to withstand day to day battering in non-critical situations. It’s always a bit of a trade-off. And part of it is just the design of the item it’s being used on. Was my use of it in that instance optimal? Could I have used something better? Redesigned the item? Whenever I make something I have to wear it for a few weeks/months and use it in its intended role to deduce what works and what doesn’t.
Another instance of one breaking, this time without any known incident that caused it.