Why does this make my player do weird things?

So, my brother sent me a gun, with a problem. It causes the player to do weird things when it's equipped. Well, it's not my scripting, so I looked at it, and don't understand what is being done exactly. So, I'm here to ask for help. The various things that happen are: The player is flung, prevented from moving for several seconds, or glitched through the floor.

OnEquipped Function

function OnEquipped(M_Icon)
	wait(math.random(10, 40) / 100)
	if Humanoid.Health ~= 0 and (not Selected) and Gun.Parent == Character then
		Selected = true
		
		BreakReload = false
		
		--------------------[ FAILSAFE RESETING ]-------------------------------------
		
		for _, GM in pairs(Ignore_Model:GetChildren()) do
			if GM.Name == "Gun_Ignore_"..Player.Name then
				GM:Destroy()
			end
		end
		
		for _,c in pairs(Connections) do
			c:disconnect()
		end
		
		Connections = {}
		
		--------------------[ CREATING IGNORE MODELS ]--------------------------------
		
		Gun_Ignore = Instance.new("Model")
		Gun_Ignore.Name = "Gun_Ignore_"..Player.Name
		Gun_Ignore.Parent = Ignore_Model
		
		--------------------[ MODIFYING THE PLAYER ]----------------------------------
		
		M_Icon.Icon = "rbxasset://textures\\Blank.png"
		
		Gui_Clone = Main_Gui:Clone()
		Gui_Clone.Parent = Player.PlayerGui
		
		SetUpGui()
		
		Shoulders.Right.Part1 = nil
		Shoulders.Left.Part1 = nil
		
		PrevNeckCF.C0 = Neck.C0
		PrevNeckCF.C1 = Neck.C1
		
		BG = Instance.new("BodyGyro", HRP)
		BG.maxTorque = VEC3(HUGE, HUGE, HUGE)
		BG.Name = "BG"
		BG.P = 1e5
		BG.cframe = CF(Torso.CFrame.p, Torso.CFrame.p + Torso.CFrame.lookVector)

		local PlayerFolder = Instance.new("Model")
		PlayerFolder.Name = "PlayerFolder"
		PlayerFolder.Parent = Gun_Ignore
		
		local AnimBase = Instance.new("Part")
		AnimBase.Transparency = 1
		AnimBase.Name = "AnimBase"
		AnimBase.CanCollide = false
		AnimBase.FormFactor = Enum.FormFactor.Custom
		AnimBase.Size = VEC3(0.2, 0.2, 0.2)
		AnimBase.BottomSurface = Enum.SurfaceType.Smooth
		AnimBase.TopSurface = Enum.SurfaceType.Smooth
		AnimBase.Parent = PlayerFolder
		
		AnimWeld = Instance.new("Weld")
		AnimWeld.Part0 = AnimBase
		AnimWeld.Part1 = Head
		AnimWeld.C0 = CF(0, 1, 0)
		AnimWeld.Parent = AnimBase
		
		local ArmBase = Instance.new("Part")
		ArmBase.Transparency = 1
		ArmBase.Name = "ArmBase"
		ArmBase.CanCollide = false
		ArmBase.FormFactor = Enum.FormFactor.Custom
		ArmBase.Size = VEC3(0.2, 0.2, 0.2)
		ArmBase.BottomSurface = Enum.SurfaceType.Smooth
		ArmBase.TopSurface = Enum.SurfaceType.Smooth
		ArmBase.Parent = PlayerFolder
		
		ABWeld = Instance.new("Weld")
		ABWeld.Part0 = ArmBase
		ABWeld.Part1 = AnimBase
		ABWeld.Parent = ArmBase
		
		local LArmBase = Instance.new("Part")
		LArmBase.Transparency = 1
		LArmBase.Name = "LArmBase"
		LArmBase.CanCollide = false
		LArmBase.FormFactor = Enum.FormFactor.Custom
		LArmBase.Size = VEC3(0.2, 0.2, 0.2)
		LArmBase.BottomSurface = Enum.SurfaceType.Smooth
		LArmBase.TopSurface = Enum.SurfaceType.Smooth
		LArmBase.Parent = PlayerFolder
		
		local RArmBase = Instance.new("Part")
		RArmBase.Transparency = 1
		RArmBase.Name = "RArmBase"
		RArmBase.CanCollide = false
		RArmBase.FormFactor = Enum.FormFactor.Custom
		RArmBase.Size = VEC3(0.2, 0.2, 0.2)
		RArmBase.BottomSurface = Enum.SurfaceType.Smooth
		RArmBase.TopSurface = Enum.SurfaceType.Smooth
		RArmBase.Parent = PlayerFolder
		
		LWeld = Instance.new("Weld")
		LWeld.Name = "LWeld"
		LWeld.Part0 = ArmBase
		LWeld.Part1 = LArmBase
		LWeld.C0 = ArmC0[1]
		LWeld.C1 = S.ArmC1_UnAimed.Left
		LWeld.Parent = ArmBase
		
		RWeld = Instance.new("Weld")
		RWeld.Name = "RWeld"
		RWeld.Part0 = ArmBase
		RWeld.Part1 = RArmBase
		RWeld.C0 = ArmC0[2]
		RWeld.C1 = S.ArmC1_UnAimed.Right
		RWeld.Parent = ArmBase
		
		LWeld2 = Instance.new("Weld")
		LWeld2.Name = "LWeld"
		LWeld2.Part0 = LArmBase
		LWeld2.Part1 = LArm
		LWeld2.Parent = LArmBase
		
		RWeld2 = Instance.new("Weld")
		RWeld2.Name = "RWeld"
		RWeld2.Part0 = RArmBase
		RWeld2.Part1 = RArm
		RWeld2.Parent = RArmBase
		
		if S.PlayerArms then
			FakeLArm = LArm:Clone()
			FakeLArm.Parent = PlayerFolder
			FakeLArm.Transparency = S.FakeArmTransparency
			FakeLArm:BreakJoints()
			
			LArm.Transparency = 1
			
			local FakeLWeld = Instance.new("Weld")
			FakeLWeld.Part0 = FakeLArm
			FakeLWeld.Part1 = LArm
			FakeLWeld.Parent = FakeLArm
			
			FakeRArm = RArm:Clone()
			FakeRArm.Parent = PlayerFolder
			FakeRArm.Transparency = S.FakeArmTransparency
			FakeRArm:BreakJoints()
			
			RArm.Transparency = 1
			
			local FakeRWeld = Instance.new("Weld")
			FakeRWeld.Part0 = FakeRArm
			FakeRWeld.Part1 = RArm
			FakeRWeld.Parent = FakeRArm
			
			Instance.new("Humanoid", PlayerFolder)
			
			for _,Obj in pairs(Character:GetChildren()) do
				if Obj:IsA("CharacterMesh") or Obj:IsA("Shirt") then
					Obj:Clone().Parent = PlayerFolder
				end
			end
		else
			local ArmTable = CreateArms()
			ArmTable[1].Model.Parent = PlayerFolder
			ArmTable[2].Model.Parent = PlayerFolder
			
			FakeLArm = ArmTable[1].ArmPart
			
			LArm.Transparency = 1
			
			local FakeLWeld = Instance.new("Weld")
			FakeLWeld.Part0 = FakeLArm
			FakeLWeld.Part1 = LArm
			FakeLWeld.Parent = FakeLArm
			
			FakeRArm = ArmTable[2].ArmPart
			
			RArm.Transparency = 1
			
			local FakeRWeld = Instance.new("Weld")
			FakeRWeld.Part0 = FakeRArm
			FakeRWeld.Part1 = RArm
			FakeRWeld.Parent = FakeRArm
		end
		--Extra gun effecting code
	end
end