Inherited a 59 after my brother passed away. This was one of his duty weapons. It will not feed or eject aluminum or steel rounds smoothly, but brass rounds shoot great. Is this a common trait? My 2 Springfields shoot them with no problems.
First, sorry about your brother's passing.
Steel and aluminum cased ammo can cause problems, as can variants in bullet weights and case sizing. If the gun has been field stripped and thoroughly cleaned and properly re-lubricated and the stoppages continue to occur, I would suggest installing a new, OEM recoil spring.
In the end, you may be relegated to using brass cased ammunition, which is what the gun was designed for.
Carter