Q. Is it ever legal to use different materials or sizes of nut, washer, standoff or non-threaded spacer up to 2.5" long?
A. Yes, this is what is stated by R11-c.
Q. Is it ever legal to use #4 or M3 screws that are up to 2.5" long made of steel or stainless steel?
A. Yes, this is what is stated by R11-a.
Q. Is it ever legal to use hollow screws that otherwise follow R11-a b and c?
A. By the strictest definitions of R11 and previous Q&A rulings on this subject, no, if purchased off-the-shelf. This minor amount of weight savings would be considered additional functionality, as well as other possible use cases like threading string through it.
Assuming the hollow screw is used as a screw (eg, no string running through it), what aspect of them makes their weight saving additional functionality, but lighter / heavier or smaller material / sizes of nuts, washers, standoffs or non threaded spacer/ smaller screws not being considered additional functionality?
Is there any guidance that can be given to find out what other hardware that seemingly follows R11 violates "additional functionality" that would make it clear that something like hollow screws are illegal?
"By the strictest definitions of R11". When should Head Referees be more strict about R11? When should they be less strict?
Thank you for your time!