Glad you found your issue. As an added comment most US aluminum comes in fractional Imperial. So likely your actual stock is what I would call “63”, which is actually 0.0625" or 1/16" thick. A similar material in the EU would be 6082 aluminum and it usually comes in Metric sizes, for the same function I would generally use 1.5mm (which is around 0.059"). Just some “gee whiz” info.
Dan