I don’t have much experience in this area i’ve only heard something that sounds conclusive to me.
The closer an object is viewed, i.e. a weapon, the more detailed it should be. After all, you have it on 1/3 of your screen and are looking directly at it.
Objects that you only look at from a distance don’t need a high poly density.
So I would say that you can’t say that in general terms. Each weapon is also differently complex in the mesh.
Always try to use as few polygons as possible as long as the quality does not drop
