diff --git a/OpenRA.Mods.Common/Effects/Bullet.cs b/OpenRA.Mods.Common/Effects/Bullet.cs
index fcdbf8fe24..396fac57cb 100644
--- a/OpenRA.Mods.Common/Effects/Bullet.cs
+++ b/OpenRA.Mods.Common/Effects/Bullet.cs
@@ -22,19 +22,22 @@ namespace OpenRA.Mods.Common.Effects
 {
 	public class BulletInfo : IProjectileInfo
 	{
-		[Desc("Projectile speed in WRange / tick, two values indicate variable velocity")]
+		[Desc("Projectile speed in WRange / tick, two values indicate variable velocity.")]
 		public readonly WRange[] Speed = { new WRange(17) };
-		public readonly string Trail = null;
-		[Desc("Maximum offset at the maximum range")]
+		[Desc("Maximum offset at the maximum range.")]
 		public readonly WRange Inaccuracy = WRange.Zero;
 		public readonly string Image = null;
 		public readonly string Palette = "effect";
 		public readonly bool Shadow = false;
+		[Desc("Trail animation.")]
+		public readonly string Trail = null;
 		[Desc("Is this blocked by actors with BlocksProjectiles trait.")]
 		public readonly bool Blockable = true;
 		[Desc("Arc in WAngles, two values indicate variable arc.")]
 		public readonly WAngle[] Angle = { WAngle.Zero };
+		[Desc("Interval in ticks between each spawned Trail animation.")]
 		public readonly int TrailInterval = 2;
+		[Desc("Delay in ticks until trail animaion is spawned.")]
 		public readonly int TrailDelay = 1;
 		public readonly int ContrailLength = 0;
 		public readonly Color ContrailColor = Color.White;
@@ -48,11 +51,11 @@ namespace OpenRA.Mods.Common.Effects
 	{
 		readonly BulletInfo info;
 		readonly ProjectileArgs args;
+		readonly Animation anim;
 		[Sync] readonly WAngle angle;
 		[Sync] readonly WRange speed;
 
-		ContrailRenderable trail;
-		Animation anim;
+		ContrailRenderable contrail;
 
 		[Sync] WPos pos, target;
 		[Sync] int length;
@@ -100,7 +103,7 @@ namespace OpenRA.Mods.Common.Effects
 			if (info.ContrailLength > 0)
 			{
 				var color = info.ContrailUsePlayerColor ? ContrailRenderable.ChooseColor(args.SourceActor) : info.ContrailColor;
-				trail = new ContrailRenderable(world, color, info.ContrailLength, info.ContrailDelay, 0);
+				contrail = new ContrailRenderable(world, color, info.ContrailLength, info.ContrailDelay, 0);
 			}
 
 			smokeTicks = info.TrailDelay;
@@ -134,7 +137,7 @@ namespace OpenRA.Mods.Common.Effects
 			}
 
 			if (info.ContrailLength > 0)
-				trail.Update(pos);
+				contrail.Update(pos);
 
 			if (ticks++ >= length || (info.Blockable && world.ActorMap
 				.GetUnitsAt(world.Map.CellContaining(pos)).Any(a => a.HasTrait<IBlocksProjectiles>())))
@@ -144,7 +147,7 @@ namespace OpenRA.Mods.Common.Effects
 		public IEnumerable<IRenderable> Render(WorldRenderer wr)
 		{
 			if (info.ContrailLength > 0)
-				yield return trail;
+				yield return contrail;
 
 			if (anim == null || ticks >= length)
 				yield break;
@@ -168,7 +171,7 @@ namespace OpenRA.Mods.Common.Effects
 		void Explode(World world)
 		{
 			if (info.ContrailLength > 0)
-				world.AddFrameEndTask(w => w.Add(new ContrailFader(pos, trail)));
+				world.AddFrameEndTask(w => w.Add(new ContrailFader(pos, contrail)));
 
 			world.AddFrameEndTask(w => w.Remove(this));
 
diff --git a/OpenRA.Mods.Common/Effects/Explosion.cs b/OpenRA.Mods.Common/Effects/Explosion.cs
index 93451480ce..4024ec6285 100644
--- a/OpenRA.Mods.Common/Effects/Explosion.cs
+++ b/OpenRA.Mods.Common/Effects/Explosion.cs
@@ -16,11 +16,11 @@ namespace OpenRA.Mods.Common.Effects
 {
 	public class Explosion : IEffect
 	{
-		World world;
+		readonly World world;
+		readonly string palette;
+		readonly Animation anim;
 		WPos pos;
 		CPos cell;
-		string palette;
-		Animation anim;
 
 		public Explosion(World world, WPos pos, string sequence, string palette)
 		{
diff --git a/OpenRA.Mods.Common/Effects/GravityBomb.cs b/OpenRA.Mods.Common/Effects/GravityBomb.cs
index 2b0184170f..0ad7c35ca6 100644
--- a/OpenRA.Mods.Common/Effects/GravityBomb.cs
+++ b/OpenRA.Mods.Common/Effects/GravityBomb.cs
@@ -22,6 +22,7 @@ namespace OpenRA.Mods.Common.Effects
 		public readonly string Palette = "effect";
 		public readonly bool Shadow = false;
 		public readonly WRange Velocity = WRange.Zero;
+		[Desc("Value added to velocity every tick.")]
 		public readonly WRange Acceleration = new WRange(15);
 
 		public IEffect Create(ProjectileArgs args) { return new GravityBomb(this, args); }
@@ -29,11 +30,12 @@ namespace OpenRA.Mods.Common.Effects
 
 	public class GravityBomb : IEffect
 	{
-		GravityBombInfo info;
-		Animation anim;
-		ProjectileArgs args;
-		WVec velocity;
-		WPos pos;
+		readonly GravityBombInfo info;
+		readonly Animation anim;
+		readonly ProjectileArgs args;
+		[Sync] WVec velocity;
+		[Sync] WPos pos;
+		[Sync] WVec acceleration;
 
 		public GravityBomb(GravityBombInfo info, ProjectileArgs args)
 		{
@@ -41,6 +43,7 @@ namespace OpenRA.Mods.Common.Effects
 			this.args = args;
 			pos = args.Source;
 			velocity = new WVec(WRange.Zero, WRange.Zero, -info.Velocity);
+			acceleration = new WVec(WRange.Zero, WRange.Zero, info.Acceleration);
 
 			anim = new Animation(args.SourceActor.World, info.Image);
 			if (anim.HasSequence("open"))
@@ -51,7 +54,7 @@ namespace OpenRA.Mods.Common.Effects
 
 		public void Tick(World world)
 		{
-			velocity -= new WVec(WRange.Zero, WRange.Zero, info.Acceleration);
+			velocity -= acceleration;
 			pos += velocity;
 
 			if (pos.Z <= args.PassiveTarget.Z)
@@ -61,7 +64,8 @@ namespace OpenRA.Mods.Common.Effects
 				args.Weapon.Impact(Target.FromPos(pos), args.SourceActor, args.DamageModifiers);
 			}
 
-			anim.Tick();
+			if (anim != null)
+				anim.Tick();
 		}
 
 		public IEnumerable<IRenderable> Render(WorldRenderer wr)
diff --git a/OpenRA.Mods.Common/Effects/LaserZap.cs b/OpenRA.Mods.Common/Effects/LaserZap.cs
index 8b30d2a6e3..5068c686a9 100644
--- a/OpenRA.Mods.Common/Effects/LaserZap.cs
+++ b/OpenRA.Mods.Common/Effects/LaserZap.cs
@@ -39,13 +39,13 @@ namespace OpenRA.Mods.Common.Effects
 
 	class LaserZap : IEffect
 	{
-		ProjectileArgs args;
-		LaserZapInfo info;
+		readonly ProjectileArgs args;
+		readonly LaserZapInfo info;
+		readonly Animation hitanim;
 		int ticks = 0;
 		Color color;
 		bool doneDamage;
 		bool animationComplete;
-		Animation hitanim;
 		WPos target;
 
 		public LaserZap(ProjectileArgs args, LaserZapInfo info, Color color)
diff --git a/OpenRA.Mods.Common/Effects/Missile.cs b/OpenRA.Mods.Common/Effects/Missile.cs
index 73f9989483..c72059dd42 100644
--- a/OpenRA.Mods.Common/Effects/Missile.cs
+++ b/OpenRA.Mods.Common/Effects/Missile.cs
@@ -31,22 +31,25 @@ namespace OpenRA.Mods.Common.Effects
 		public readonly WAngle MaximumPitch = WAngle.FromDegrees(30);
 		[Desc("How many ticks before this missile is armed and can explode.")]
 		public readonly int Arm = 0;
-		public readonly string Trail = null;
 		[Desc("Is the missile blocked by actors with BlocksProjectiles: trait.")]
 		public readonly bool Blockable = true;
 		[Desc("Maximum offset at the maximum range")]
 		public readonly WRange Inaccuracy = WRange.Zero;
 		[Desc("Probability of locking onto and following target.")]
 		public readonly int LockOnProbability = 100;
-		[Desc("Explode when following the target longer than this.")]
 		[Desc("In n/256 per tick.")]
 		public readonly int RateOfTurn = 5;
+		[Desc("Explode when following the target longer than this many ticks.")]
 		public readonly int RangeLimit = 0;
+		[Desc("Trail animation.")]
+		public readonly string Trail = null;
+		[Desc("Interval in ticks between each spawned Trail animation.")]
 		public readonly int TrailInterval = 2;
 		public readonly int ContrailLength = 0;
 		public readonly Color ContrailColor = Color.White;
 		public readonly bool ContrailUsePlayerColor = false;
 		public readonly int ContrailDelay = 1;
+		[Desc("Should missile targeting be thrown off by nearby actors with JamsMissiles.")]
 		public readonly bool Jammable = true;
 		[Desc("Explodes when leaving the following terrain type, e.g., Water for torpedoes.")]
 		public readonly string BoundToTerrainType = "";
@@ -65,7 +68,7 @@ namespace OpenRA.Mods.Common.Effects
 		readonly Animation anim;
 
 		int ticksToNextSmoke;
-		ContrailRenderable trail;
+		ContrailRenderable contrail;
 
 		[Sync] WPos pos;
 		[Sync] int facing;
@@ -109,7 +112,7 @@ namespace OpenRA.Mods.Common.Effects
 			if (info.ContrailLength > 0)
 			{
 				var color = info.ContrailUsePlayerColor ? ContrailRenderable.ChooseColor(args.SourceActor) : info.ContrailColor;
-				trail = new ContrailRenderable(world, color, info.ContrailLength, info.ContrailDelay, 0);
+				contrail = new ContrailRenderable(world, color, info.ContrailLength, info.ContrailDelay, 0);
 			}
 		}
 
@@ -127,7 +130,8 @@ namespace OpenRA.Mods.Common.Effects
 		public void Tick(World world)
 		{
 			ticks++;
-			anim.Tick();
+			if (anim != null)
+				anim.Tick();
 
 			// Missile tracks target
 			if (args.GuidedTarget.IsValidFor(args.SourceActor) && lockOn)
@@ -165,7 +169,7 @@ namespace OpenRA.Mods.Common.Effects
 			}
 
 			if (info.ContrailLength > 0)
-				trail.Update(pos);
+				contrail.Update(pos);
 
 			var cell = world.Map.CellContaining(pos);
 
@@ -183,7 +187,7 @@ namespace OpenRA.Mods.Common.Effects
 		void Explode(World world)
 		{
 			if (info.ContrailLength > 0)
-				world.AddFrameEndTask(w => w.Add(new ContrailFader(pos, trail)));
+				world.AddFrameEndTask(w => w.Add(new ContrailFader(pos, contrail)));
 
 			world.AddFrameEndTask(w => w.Remove(this));
 
@@ -197,7 +201,7 @@ namespace OpenRA.Mods.Common.Effects
 		public IEnumerable<IRenderable> Render(WorldRenderer wr)
 		{
 			if (info.ContrailLength > 0)
-				yield return trail;
+				yield return contrail;
 
 			if (!args.SourceActor.World.FogObscures(wr.World.Map.CellContaining(pos)))
 			{