Thanks for the replies -
electrathon - Bladetech and I think Galco both use a kind of directional snap - not sure what they are called - anyway they work really well for 1911 mag holders and similar equipment. 8 rounds of 1911 ammo is not as heavy as some of my knives, but I think it's a good proof of concept for the design - I've used them many years without issue. I may have trouble finding a source, I don't know yet.
I'll have to try a liner, as you and camano suggest - I had never heard of the covers, I'll check those out also.
Harag, I have tried that on one sheath for a personal knife, so I'm not an expert, but it did not work for me. It lessened the scratching, but would have still ruined a damascus or acid etched blade.
thanks again for your time