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code/datums/ammo/ammo.dm

@@ -89,6 +89,9 @@
 	/// 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"
 
+	/// How much fire delay to add to the weapon after firing this kind of ammo
+	var/fire_delay_modifier = 0
+
 /datum/ammo/New()
 	set_bullet_traits()
 

code/datums/ammo/bullet/revolver.dm

@@ -25,10 +25,10 @@
 	damage = 35
 	penetration = ARMOR_PENETRATION_TIER_4
 	accuracy = HIT_ACCURACY_TIER_3
+	fire_delay_modifier = 1 SECONDS
 
-/datum/ammo/bullet/revolver/heavy/on_hit_mob(mob/entity, obj/projectile/bullet)
-	slowdown(entity, bullet)
-	pushback(entity, bullet, 4)
+/datum/ammo/bullet/revolver/heavy/on_hit_mob(mob/M, obj/projectile/P)
+	knockback(M, P, 4)
 
 /datum/ammo/bullet/revolver/incendiary
 	name = "incendiary revolver bullet"

code/modules/projectiles/gun.dm

@@ -1142,6 +1142,8 @@ and you're good to go.
 		flags_gun_features &= ~GUN_BURST_FIRING
 		return NONE
 
+	var/ammo_fire_delay = projectile_to_fire.ammo.fire_delay_modifier // Save this early because projectile_to_fire is going to be nulled
+
 	apply_bullet_effects(projectile_to_fire, user, reflex, dual_wield) //User can be passed as null.
 	SEND_SIGNAL(projectile_to_fire, COMSIG_BULLET_USER_EFFECTS, user)
 
@@ -1204,7 +1206,7 @@ and you're good to go.
 		if(check_for_attachment_fire)
 			active_attachable.last_fired = world.time
 		else
-			last_fired = world.time
+			last_fired = world.time + ammo_fire_delay
 			var/delay_left = (last_fired + fire_delay + additional_fire_group_delay) - world.time
 			if(fire_delay_group && delay_left > 0)
 				LAZYSET(user.fire_delay_next_fire, src, world.time + delay_left)