Purchased to drill holes in 13" masonry with a 4" dry drill bit. About halfway through, the core seemed to wobble. I removed the chisel and found that the shank on this adapter was deformed (twisted) from the torsional action of drilling and was also slightly bent. I have not used this on a hardcore core drill. I used a Milwaukee Plumbers hand drill. The material "succumbed" and irrevocably deformed by simple manual drilling. I must say that the material this adapter is made of does not have sufficient strength to be used for its intended purpose.