Dimensions causing the problems are width and thickness.
Shape-dimension at anodized slot is the real problem. Thickness is part of the problem. Barrels' armoring has ribs. Ribs project too close to barrels' anodized slots. This forces tacky strap to convolute and rub against armor. Were the strap slightly thinner, AND made of more friction free material, problem is solved.
Width is .431 inch (10.925 mm)
Strap is OK for width. Were I making one from scratch, I would use a wider piece of material (for around my neck) and reduce width where it enters slots to correct width.
Thickness, not at punched hole is .075 inch (1.90 mm)
Thickness AT punched hole is .078 inch (1. 98 mm)
On my Zeiss-Jena 7 x 40 EDFs the material was some sort of woven polyester. While too thick to use on 8 x 30s, material didn't bind.
I believe I will look at woven Kevlar, then at woven Teflon, if Kevlar is unsatisfactory. Ordering from optical/camera supply shop is non-starter. Rather than plug in a strap that's already doing this job, I'll look for a strap/material that meets my specifications, then adapt it to the job.
Easier, probably less expensive.