Some ammo fixes

- Fixes pirate gun not getting 12g caliber correctly.
- Fixes .357 caliber not being named consistently with everything else.
(Do not merge this until
https://github.com/PolarisSS13/Polaris/pull/3533 is merged pls, unless
Yosh fixes his caliber to be correct also.)
- Changes .50AE ammo to .44 because that's more consistent with what the
gun is capable of in-game, because it uses the same damage values as the
.357 and not a bullet that shoots through through your fridge, through
your house, and hits your neighbor's home invader like a .50AE is IRL.
The fact that it's .44 makes much more sense. This is purely a fluff
change because it annoyed me.
- Fixes a bunch of ammo.dmi icon names and makes the file not a jumbled
fucking mess. This means now your 762 mags and the newly renamed 44 mags
will not be broken anymore.

code/modules/projectiles/guns/projectile.dm

@@ -11,7 +11,7 @@
 	matter = list(DEFAULT_WALL_MATERIAL = 1000)
 	recoil = 1
 
-	var/caliber = "357"		//determines which casings will fit
+	var/caliber = ".357"		//determines which casings will fit
 	var/handle_casings = EJECT_CASINGS	//determines how spent casings should be handled
 	var/load_method = SINGLE_CASING|SPEEDLOADER //1 = Single shells, 2 = box or quick loader, 3 = magazine
 	var/obj/item/ammo_casing/chambered = null