My Little brothers Marlin Model 60 22.lr semiautomatic rifle keeps jamming.?

If you have not done so try different ammo. 22 lr semi auto's are typically picky on what ammo they shoot well. I have found that cci mini-mags work in most 22's. If it still doesn't work with different ammo then call marlin and explain the problem. If its a new gun they will fix it.