I got the 1" rotary hammer drill from Harbor Freight and am drilling 5/8" holes and am installing railing around some precast steps using 3/8 lead bolt anchors and every hole I drill blows out the concrete on the back side of the holes. I have to drill clear thru because the steps are only 2-1/2" thick in most spots. Is there a diamond hole drill less aggressive or a different method. I won't have much steps left as they'll be all busted up by the time I get the railing mounted. Help. Thanks bjr23