Fix shadow AP bonus (#3065)

<!-- Write **BELOW** The Headers and **ABOVE** The comments else it may
not be viewable. -->
<!-- You can view Contributing.MD for a detailed description of the pull
request process. -->

## About The Pull Request

This was being applied to the casing

## Why It's Good For The Game

I know the brass is hot but i think the burning does better in the
bullet

## Changelog

:cl:
fix: The shadow's gunslinger buff now properly provides an AP bonus
/:cl:

<!-- Both :cl:'s are required for the changelog to work! You can put
your name to the right of the first :cl: if you want to overwrite your
GitHub username as author ingame. -->
<!-- You can use multiple of the same prefix (they're only used for the
icon ingame) and delete the unneeded ones. Despite some of the tags,
changelogs should generally represent how a player might be affected by
the changes rather than a summary of the PR's contents. -->

Signed-off-by: Theos <[email protected]>

code/modules/projectiles/guns/ballistic/revolver.dm

@@ -727,4 +727,4 @@ EMPTY_GUN_HELPER(revolver/detective)
 	// if you go through the pain of not only using this shitty gun, but also with the fucking gunslinger quirk, you deserve this bonus. not a BIG bonus, but enough as an incentive to make people actually take the quirk.
 	if(chambered.BB && (HAS_TRAIT(user, TRAIT_GUNSLINGER)))
 		chambered.BB.damage += 5
-		chambered.armour_penetration += 5
+		chambered.BB.armour_penetration += 5