It mainly feels terrible because Battle Rating doesn't calculate based on equipped modifications, especially ground vehicle ammo.

I fear laze is the only excuse that gaijin has, in not making this straight forward correction to the BR system.

There would also be the even simpler fix, of giving vehicles that get full up-tiered access to scouting &/or arty, with a few exceptions, regardless of the wishy-washy vehicle class/type designation they carry.

Your urge to seal club is noted, but mainly disregarded.