This is kind of on topic: is there an industry standard for the relationship between the actual hole size and the nominal pin size? Like how much of an interference fit (after the pin deforms in installation) is the norm…
It seems to me that there might be different standards for slotted and coil pins because of how much each can compress.
I’ve always thought that where an AR part needed to be secured for heavy duty purposes, a solid pin, or even a taper pin was used. Slotted roll pins, on the other hand, seem to be there for “holding something in place” like the gas tube, or “giving something an axle to move on without having to deal with threaded fasteners” like the trigger guard or bolt catch.
None of the places that have roll pins in an AR seem to have any strong forces applied to them. Conversely, whatever type of pin is there, that pin’s job is to stay put. I find it interesting that there are well developed commercial kits to replace the bolt catch pin with a threaded fastener, and all of them have to work at not coming loose because the catch pivots.
Notice how I’m not invoking Saint Stoner and how “in his wisdom” he did this or that…instead I’m thinking of the industrial design aspect, and how one roll pin replaces a screw, a nut, and some way to lock them together.