How do the guns from phantom forces work?

Hello, I want to make a gun, however the tool system roblox has is really ugly. I noticed phantom forces guns are literal god tier but impossible to create. It’s almost like they sold their souls to the devil and the devil himself spawned the guns.

So how does phantom forces achieve the impossible? The way they do their guns is not possible on roblox so how did they do it? Did they weld the guns to the players hands? because that doesn’t work:

	local gun = game.ServerStorage.Model:Clone()
	gun.Parent = plr.Character
	local HandRightWeld ="WeldConstraint")
	local HandLeftWeld ="WeldConstraint")
	local RightHand = nil
	local LeftHand = nil
	if plr.Character:FindFirstChild("Right Arm") then
		RightHand = plr.Character:FindFirstChild("Right Arm")
		LeftHand = plr.Character:FindFirstChild("Light Arm")
	elseif plr.Character:FindFirstChild("RightHand") then
		RightHand = plr.Character:FindFirstChild("RightHand")
		LeftHand = plr.Character:FindFirstChild("LeftHand")
		error("something went wrong")
	HandRightWeld.Parent = RightHand
	HandRightWeld.Part0 = RightHand
	HandRightWeld.Part1 = gun.Hand1
	HandRightWeld.Parent = LeftHand
	HandRightWeld.Part0 = LeftHand
	HandRightWeld.Part1 = gun.Hand2

They welded the guns to the player’s torsos and did animations. It is actually really easy to get good looking guns with a custom equip system. Most of roblox’s engine aside from rendering, physics, and lighting, (like the tool system or startergui) can be completely overwritten with your own scripts.