Bart, The match Regs I posted included Camp Perry Palma rifle 800,900,1000yd and that match you shoot.
I also found Palma rifle you can have lens.
Front Sight)—A lens and/or filter may be used in conjunction with the front and/or rear sight.(Rear Sight)— A corrective lens may be placed inside the rear sight hood on service rifles conforming to Rule 3.1. No part of the lens or method of installing the lens may protrude outside the rear sight hood.
What's the purpose of a corrective lens in the front and/or rear sight?
They're allowed most of the time with metallic sights on most rifle types. Details explained in the NRA Rule Books:
https://competitions.nra.org/competition-resources/rule-books/
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