Damage being reverted by gun randomly?

In the LocalScript of my gun, the hit detection of the bullet is the following code:

	missile.Touched:connect(function(hit)
		if hit.CanCollide ~= false or hit.Name == "Right Leg" or hit.Name == "Left Leg" or hit.Name == "Left Arm" or hit.Name == "Right Arm" then
			if hit.Transparency ~= 1 then -- The above could lag?
				local E = Instance.new("Explosion")
				E.BlastPressure = S.ExplosionPressure
				E.BlastRadius = S.ExplosionRadius
				E.DestroyJointRadiusPercent = (S.RangeBasedDamage and 0 or 1)
				E.ExplosionType = S.ExplosionType
				E.Position = missile.Position
				E.Parent = game.Workspace
		      		E.Hit:connect(function(hitPart, partDistance)
					if (not hitPart:IsDescendantOf(Character)) then
				    	local humanoid = hitPart.Parent and 		              hitPart.Parent:FindFirstChild("Humanoid")
				    	if humanoid then
							if humanoid.Name ~= script.Parent.Parent.Name then
					        	        local distance_factor = partDistance / E.BlastRadius
					        	        distance_factor = 1 - distance_factor                       
					        	        humanoid:TakeDamage(damage*distance_factor)
							end               
				    	end
					end
				end) 
				
				
				--HitSound:Play()
				missile.Parent = nil
			end
		end
	end)

For some reason, at random, the bullet's damage will be reverted. For example, I'll shoot someone. Deals damage like normal. Shoot again, and for a split second, it looks like i've damaged them (health bar), but then reverts back to the health they had before.

Any ideas? Thanks!