Ports tg#84247: Fixes magazine overflow and russian roulette starting with 6(7) bullets

[francinum]

tgstation/tgstation#84247

About The Pull Request

Box magazine code started from .len instead of .len + 1 when refilling mags which would be fine if BYOND's to didn't include the last number. Unfortunately, it does, and if the mag has bullets when its refilled it will have one over the limit.

Russian revolver code had a type typo where ammo was added in nonexistent /obj/item/ammo_box/magazine/internal/rus357's Initialize instead of /obj/item/ammo_box/magazine/internal/cylinder/rus357. It was pretty clearly was meant to start with a single bullet instead of 6, but neither removing existing ammo nor adding new was implemented properly. I stuff it with 5 blanks instead of making it empty because this will at least allow it to click with current guncode instead of bashing yourself over the head without any feedback, until I rework it.

Changelog

🆑 SmArtKar
fix: Guns no longer can be overfilled by 1 bullet
fix: Russian revolvers now spawn with only 1 live round as originally intended, and click when firing a blank.
/:cl: