To add a couple of thots re warranty. Few are the warranties that one doesn't have to fight for. Normally, its limited to auto extended warranties. Like any insurance business, they need to make a profit to continue in business and the potential for hassle exists.
On my tube type RDs as well as my scopes, I'm careful in mounting. I'm concerned about appearances particularly if having to send in for warranty service. Warranty puts 'them' in charge. 'They' have the power in the relationship. Given that, I avoid stainsless finishes as they show 'ring' marks easier. I line the inner side of the rings w/scotch tape and careful about over tightening of screws that may cause/contribute to lens fracture. Nowadays, I use a torque driver to assure proper tightness. Maybe just lucky but I've never had to use locktite, epoxy or upgrade to larger screws. I try to do more than my part so to help facilitate 'them' doing their part.