Wire for 50A 220V Service - 110' run

I thought that the main problem with aluminum wire, at least back in the 70s when they used it in houses, was that it expanded under the screws holding it to receptacles and caused the screws to back out, creating a gap and resulting heat and fires. their cure was to use a piece of copper wire at the receptacle and hooked that up to the main run of aluminum.
copper clad aluminum is still legal AFAIK.
bumpy