Agreed, they won't fit. I've got some of the "Box-mod" 510s here, and there's no way that making that pin only 3mm longer would make it usable in the 510 insert that the mod's upper us currently designed to accept because..Too bad they don't fit the 510 ' s this mod needs.
Right!They appear too short anyways, need to be longer
Moreover, these pins look to be brass. If you're willing to run your juice through a brass pin, just get some brass 6-32 screws -- they'd be MUCH easier to drill than the stainless steel one's we're using now.