Since theres inverted flares on these , the threads dont Really hold any pressure Listen to Mr Bill 62 maxwagon This is the proper way - if you cant titen them properly
Generally the use of copper is avoided with gasoline use, as the gasoline with slowly dissolution the copper and actually "plate" the fuel system/carbs/etc with copper thru an electroless process
not to mention you have now doubled the sealing surfaces and potential for leaks
