My current project has some 3/8" square holes. I watched David Charleston's latest DVD where he stresses keeping the chisel vertical and striking it with a vertical blow. Having only light weight hammers and my hand/eye skills could qualify me for handicap parking so I came up with the idea of using a 10 pound dumbell. I hold it above the chisel and when the chisel is vertical I release my grip on the dumbell. The 10 pound blow works quite well on the QSWO.