Raycast part isn't resizing correctly

Help and Feedback Scripting Support
1

Sometimes it overshoots and goes through the part that is being aimed at, and sometimes it undershoots and does not reach the part. Why is this happening and how can I fix it? Here’s my script:

--Determines the size of the part based on two Vector3s.
local function setBeamLength(beam, hit)
	local distance = (((beam.Position) - hit).Magnitude)
	print(distance)
	beam.Size = Vector3.new(distance, 1, 1)
end

--Creates the beam iteself and offsets its position relative to the player's right arm.
local function createFastAttackBeam(plr, hit)
	local beam = replicatedStorage:FindFirstChild("Lightning"):Clone()
	local char = plr.Character
	local rightArm = char:FindFirstChild("Right Arm")
	setBeamLength(beam, hit)
	local offset = CFrame.new(((beam.Size.X / 2) + 4), 0, 0)
	beam.CFrame = (CFrame.lookAt(rightArm.Position, hit) * CFrame.Angles(math.rad(0), math.rad(90), math.rad(0))):ToWorldSpace(offset)
	beam.Parent = game.Workspace
	createFadeBeam(beam) --Tweens the beams size/transparency out, does not effect length.
end
2

¿Are you using “hit” argument as your ray result Instance or Position?

3

It’s a position. ​​​​​​​​​​​​​​​​​​​