Justify? Really? LOL! You can never have too many guns, ammo, water, toilet paper.
I guess it might be hard to have too many weapons. I have a good range of weapons for all situations and enough mags/speed loaders etc., to do the job - same with ammo, but ammo can be fluid depending on field/range time.
If it gives one pleasure to "Burt Gummer" it, then I say, "Be Happy!"