Fixes issue #7499.

Normalized all ammo counts to 30.

Not the author of this mod, but made a gut-feel fix to things.
Looking at the recipes, I think the author was trying to make the
"better" bullets cost more and mistakenly had the bullets cost more
casing/primers (or perhaps it was just a copy-paste error).

Also noted that the mod is missing a recipe for the 6.54x42mm 9N12 ammo,
and this checkin does not add that.
Merge pull request #7742 from jeremyosborne/549x39_recipe_inconsistent

Fixes issue #7499.