A few little things

code/datums/ammo/ammo.dm

@@ -89,8 +89,8 @@
 	/// The flicker that plays when a bullet hits a target. Usually red. Can be nulled so it doesn't show up at all.
 	var/hit_effect_color = "#FF0000"
 
-	/// currently responsible for increasing firing sound volume ONLY
-	var/special = FALSE
+	/// Changes the freq of firing sound based on ammo type
+	var/firing_freq_offset = FALSE
 
 /datum/ammo/New()
 	set_bullet_traits()

code/datums/ammo/bullet/shotgun.dm

@@ -162,7 +162,7 @@
 	damage = 140
 	penetration = ARMOR_PENETRATION_TIER_4
 	bonus_projectiles_amount = EXTRA_PROJECTILES_TIER_6
-	special = TRUE
+	firing_freq_offset = SOUND_FREQ_LOW
 
 //buckshot variant only used by the masterkey shotgun attachment.
 /datum/ammo/bullet/shotgun/buckshot/masterkey
@@ -197,7 +197,7 @@
 	max_range = 8
 	damage = 140
 	penetration = ARMOR_PENETRATION_TIER_4
-	special = TRUE
+	firing_freq_offset = SOUND_FREQ_LOW
 
 /*
 					8 GAUGE SHOTGUN AMMO

code/datums/skills/uscm.dm

@@ -290,6 +290,7 @@ COMMAND STAFF
 		SKILL_VEHICLE = SKILL_VEHICLE_SMALL,
 		SKILL_JTAC = SKILL_JTAC_EXPERT,
 		SKILL_INTEL = SKILL_INTEL_TRAINED,
+		SKILL_SURGERY = SKILL_SURGERY_NOVICE,
 	)
 
 /datum/skills/SEA

code/modules/projectiles/gun.dm

@@ -1677,9 +1677,12 @@ not all weapons use normal magazines etc. load_into_chamber() itself is designed
 
 	projectile_to_fire.shot_from = src
 
-	return 1
+	if(user)
+		projectile_to_fire.firer = user
+		if(isliving(user))
+			projectile_to_fire.def_zone = user.zone_selected
 
-#define SPECIAL_AMMUNITION_FIRING_VOLUME 100
+	return 1
 
 /obj/item/weapon/gun/proc/play_firing_sounds(obj/projectile/projectile_to_fire, mob/user)
 	if(!user) //The gun only messages when fired by a user.
@@ -1692,13 +1695,10 @@ not all weapons use normal magazines etc. load_into_chamber() itself is designed
 	if(projectile_to_fire.ammo && projectile_to_fire.ammo.sound_override)
 		actual_sound = projectile_to_fire.ammo.sound_override
 
-	projectile_to_fire.firer = user
-	if(isliving(user))
-		projectile_to_fire.def_zone = user.zone_selected
-
 	//Guns with low ammo have their firing sound
 	var/firing_sndfreq = (current_mag && (current_mag.current_rounds / current_mag.max_rounds) > GUN_LOW_AMMO_PERCENTAGE) ? FALSE : SOUND_FREQ_HIGH
-	var/sound_volume = in_chamber.ammo.special ? SPECIAL_AMMUNITION_FIRING_VOLUME : firesound_volume
+
+	firing_sndfreq = in_chamber.ammo.firing_freq_offset ? in_chamber.ammo.firing_freq_offset : firing_sndfreq
 
 	//firing from an attachment
 	if(active_attachable && active_attachable.flags_attach_features & ATTACH_PROJECTILE)
@@ -1707,14 +1707,12 @@ not all weapons use normal magazines etc. load_into_chamber() itself is designed
 	else
 		if(!(flags_gun_features & GUN_SILENCED))
 			if (firing_sndfreq && fire_rattle)
-				playsound(user, fire_rattle, sound_volume, FALSE)//if the gun has a unique 'mag rattle' SFX play that instead of pitch shifting.
+				playsound(user, fire_rattle, firesound_volume, FALSE) //if the gun has a unique 'mag rattle' SFX play that instead of pitch shifting.
 			else
-				playsound(user, actual_sound, sound_volume, firing_sndfreq)
+				playsound(user, actual_sound, firesound_volume, firing_sndfreq)
 		else
 			playsound(user, actual_sound, 25, firing_sndfreq)
 
-#undef SPECIAL_AMMUNITION_FIRING_VOLUME
-
 /obj/item/weapon/gun/proc/simulate_scatter(obj/projectile/projectile_to_fire, atom/target, turf/curloc, turf/targloc, mob/user, bullets_fired = 1)
 	var/fire_angle = Get_Angle(curloc, targloc)
 	var/total_scatter_angle = projectile_to_fire.scatter