I bought a 5/8 Bosch masonry chisel to drill 2 and 1/4 inch long holes in a concrete floor slab [the holes are designed for installing 1/2" (OD) stick-in anchors. As a DIYer, my impact drill is only 5.4 amps and I was concerned that maybe a 5/8 bit would be too big for the drill. In fact, with the 5/8 it was -Bit excruciatingly slow compared to the 1/4" bit I tried next. Luckily I decided to experiment with the 1/4 hole as a pilot hole for the 5/8 bit and it made one big difference. The 5/8 bit didn't wander, it just followed the pilot hole. To make a long story short, for those of you with less powerful punchers, you can make a pilot hole first [I suspect bit sizes other than 1/4 "also other smaller ones e bit sizes like 3/16, 5/16, 3/8 may be suitable for pilot holes].