The Problem 1

local aimCount = 0;
local offset = weapon.Handle.CFrame:inverse() * weapon.Aim.CFrame;

local function aimDownSights(aiming)
	local start = joint.C1;
	local goal = aiming and joint.C0 * offset or CFrame.new();

	aimCount = aimCount + 1;
	local current = aimCount;
	for t = 0, 101, 10 do
		if (current ~= aimCount) then break; end
		game:GetService("RunService").RenderStepped:Wait();
		joint.C1 = start:Lerp(goal, t/100);
	end
end

local function onInputBegan(input, process)
	if (process) then return; end
	if (input.UserInputType == Enum.UserInputType.MouseButton2) then
		aimDownSights(true);
	end
end

local function onInputEnded(input, process)
	if (process) then return; end
	if (input.UserInputType == Enum.UserInputType.MouseButton2) then
		aimDownSights(false);
	end
end

game:GetService("UserInputService").InputBegan:Connect(onInputBegan);
game:GetService("UserInputService").InputEnded:Connect(onInputEnded);