Tank IFF, Minigun tweaks, code cleanup & new hitsound (#6688)

# About the pull request

* Adds IFF to the Minigun
* Changes used projectile icon for Minigun
* Adds scatter decrease to Minigun with windup
* increases firing speed of the minigun
* increases rev up time of the minigun
* Puts Minigun bullet code into the tank ammo file, for organisation.
* Adds hitsound for Autocannon Flakbullets
* Adds new projectile icon for Autocannon
* Fixes code for UPP minigun ammo

# Explain why it's good for the game

The Minigun for the Tank is lacking IFF for no good reason. Its a left
over from old code and isnt adjusted for its current state.
This should make the Minigun less ass to use, and also make the Minigun
a better choice overall.
The autocannon keeps FF, to have to role of a more high risk/high damage
weapon. Its semi automatic, so it can affort not getting IFF.

The Minigun also gets thigther spread as it spins up. It starts at a
higher spread in turn.
The full time to achive full spin has also been increased by 2 seconds,
and the overall firingspeed has been very very sligthly increased.
This overall should make the minigun a very good support weapon. Baiscly
the SGs bigger cousin, just that the gun is actually fun. I hope. to
eleate it being the SGs bigger cousin, the gun now no longer has smaller
projectile sprites then the SG. Autocannon also gets new sprites fitting
for its 20mm rounds.
These changes should elevate the minigun to become a more stable pick
and less of a noob trap.

The new hitsound is sampeld straigth from pixabay or our repo. So no
legal troubles there.

Thanks to cuberound that helped with the minigun scatter code

# Testing Photographs and Procedure

<details>
<summary>Screenshots & Videos</summary>

![grafik](https://github.com/user-attachments/assets/ebca5e74-6a3e-4e35-a288-613e550d094b)


</details>


# Changelog
:cl: TheManWithNoHands
balance: IFF, scatter based on minigun rev up, rev up time increase,
firing delay decrease
code: Places minigun aMmo in the Tank ammo File
soundadd: adds a hit sound for 20mm flak
/:cl:

---------

Co-authored-by: harryob <[email protected]>

code/datums/ammo/bullet/special_ammo.dm

@@ -149,15 +149,10 @@
 		RegisterSignal(SSdcs, COMSIG_GLOB_MODE_PRESETUP, PROC_REF(setup_hvh_damage))
 
 /datum/ammo/bullet/minigun/proc/setup_hvh_damage()
+	SIGNAL_HANDLER
 	if(MODE_HAS_FLAG(MODE_FACTION_CLASH))
 		damage = 15
 
-/datum/ammo/bullet/minigun/tank
-	accuracy = -HIT_ACCURACY_TIER_1
-	accuracy_var_low = PROJECTILE_VARIANCE_TIER_8
-	accuracy_var_high = PROJECTILE_VARIANCE_TIER_8
-	accurate_range = 12
-
 /datum/ammo/bullet/m60
 	name = "M60 bullet"
 	headshot_state = HEADSHOT_OVERLAY_MEDIUM

code/datums/ammo/bullet/tank.dm

@@ -4,9 +4,12 @@
 //======
 */
 
+//Autocannon Ammo//
+
 /datum/ammo/bullet/tank/flak
 	name = "flak autocannon bullet"
 	icon_state = "autocannon"
+	sound_hit  = 'sound/weapons/sting_boom_small1.ogg'
 	damage_falloff = 0
 	flags_ammo_behavior = AMMO_BALLISTIC
 	accurate_range_min = 4
@@ -72,3 +75,30 @@
 	for(var/mob/living/carbon/L in T)
 		if(L.stat == CONSCIOUS && L.mob_size <= MOB_SIZE_XENO)
 			shake_camera(L, 1, 1)
+
+//Minigun Ammo//
+
+/datum/ammo/bullet/tank/minigun
+	name = "minigun bullet"
+	headshot_state = HEADSHOT_OVERLAY_MEDIUM
+	icon_state = "bullet_large"
+
+	accuracy = -HIT_ACCURACY_TIER_1
+	accuracy_var_low = PROJECTILE_VARIANCE_TIER_8
+	accuracy_var_high = PROJECTILE_VARIANCE_TIER_8
+	accurate_range = 12
+	damage = 40
+	penetration = ARMOR_PENETRATION_TIER_6
+	damage_armor_punch = 1
+
+/datum/ammo/bullet/tank/minigun/New()
+	..()
+	if(SSticker.mode && MODE_HAS_FLAG(MODE_FACTION_CLASH))
+		damage = 15
+	else if(SSticker.current_state < GAME_STATE_PLAYING)
+		RegisterSignal(SSdcs, COMSIG_GLOB_MODE_PRESETUP, PROC_REF(setup_hvh_damage))
+
+/datum/ammo/bullet/tank/minigun/proc/setup_hvh_damage()
+	SIGNAL_HANDLER
+	if(MODE_HAS_FLAG(MODE_FACTION_CLASH))
+		damage = 15

code/modules/vehicles/hardpoints/hardpoint_ammo/minigun_ammo.dm

@@ -5,6 +5,6 @@
 	caliber = "7.62x51mm" //Correlates to miniguns
 	icon_state = "painless"
 	w_class = SIZE_LARGE //Primary weapon ammo should probably all be the same w_class
-	default_ammo = /datum/ammo/bullet/minigun/tank
+	default_ammo = /datum/ammo/bullet/tank/minigun
 	max_rounds = 500
 	gun_type = /obj/item/hardpoint/primary/minigun

code/modules/vehicles/hardpoints/primary/minigun.dm

@@ -26,16 +26,16 @@
 		"8" = list(-77, 0)
 	)
 
-	scatter = 7
+	scatter = 18
 	gun_firemode = GUN_FIREMODE_AUTOMATIC
 	gun_firemode_list = list(
 		GUN_FIREMODE_AUTOMATIC,
 	)
-	fire_delay = 0.8 SECONDS //base fire rate, modified by stage_delay_mult
+	fire_delay = 0.7 SECONDS //base fire rate, modified by stage_delay_mult
 
 	activation_sounds = list('sound/weapons/gun_minigun.ogg')
 	/// Active firing time to reach max spin_stage.
-	var/spinup_time = 8 SECONDS
+	var/spinup_time = 10 SECONDS
 	/// Grace period before losing spin_stage.
 	var/spindown_grace_time = 2 SECONDS
 	COOLDOWN_DECLARE(spindown_grace_cooldown)
@@ -52,7 +52,7 @@
 
 /obj/item/hardpoint/primary/minigun/set_fire_delay(value)
 	fire_delay = value
-	SEND_SIGNAL(src, COMSIG_GUN_AUTOFIREDELAY_MODIFIED, fire_delay * stage_delay_mult)
+	SEND_SIGNAL(src, COMSIG_GUN_AUTOFIREDELAY_MODIFIED, fire_delay * stage_delay_mult, scatter * stage_delay_mult)
 
 /obj/item/hardpoint/primary/minigun/set_fire_cooldown()
 	calculate_stage_delay_mult() //needs to check grace_cooldown before refreshed
@@ -79,5 +79,11 @@
 	var/new_stage_rate = stage_rate[floor(spin_stage)]
 
 	if(old_stage_rate != new_stage_rate)
+		scatter = initial(scatter) * (1/new_stage_rate)
 		stage_delay_mult = 1 / new_stage_rate
 		SEND_SIGNAL(src, COMSIG_GUN_AUTOFIREDELAY_MODIFIED, fire_delay * stage_delay_mult)
+
+/obj/item/hardpoint/primary/minigun/set_bullet_traits()
+	LAZYADD(traits_to_give, list(
+		BULLET_TRAIT_ENTRY(/datum/element/bullet_trait_iff)
+	))