The bolt on a semi-auto rifle is called the bolt and that handle is called the bolt handle. The 66 doesn't really have a hammer; the piece that flies forward when the trigger is pulled is called the "firing pin striker" by Remington.
I am not sure what ammo would have to do with the bolt going back into battery, but certainly a change of ammo won't hurt and might help. That gun was really made for regular 40 grain .22 LR, regular or high speed.
Jim
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