Thank you very much for the assistance. I'll change his guns.

The New mexico used to be able to use the 16's but it got a nerf and can only use the 14"
triple guns now. :/

Exactly.

The NM-45 has 365 space for each of it's R mounts. This fits the triple 14"/45 mk10L guns
(330 space) with enough leftover space to fit 5 binds of ammo (35 space). If you put on
the 16"/50 mk2L guns (358 space), there is not enough room left for even 1 bind of ammunition.

(14" ammo takes 7 space per bind, 16" ammo takes 8 space per bind, and you want 4 binds or
more for most games (or 3 binds if using dual guns instead of triples).)

try a lower level gun you have no room left

It sounds like your cousin is trying to use the dual 16" Mark 2 L. Those are for the
Colorado (and maybe Tennessee 1945). For the New Mexico 1945, you want the level 70
triple 14" Mark 7 guns.

I don't have a NM but i'll give it a try. Maybe the guns your cousin chose has no more
space to handle any ammo.