it depends what there is under the rifle as its on the ground . there could be a block of wood between the rifle and the concrete that you cant see
you would have to take the risk then
it depends on the rifle condition and age i guess .if it was a doer upper and needed the stock refinished then i would buy it . not a brand newish one . but to be honest you do not know the history of ANY used rifle that is for sale . it could have been dropped on a carpeted area or on the grass and you never know until you bought it and it shot funny .