I built one this afternoon. I tried the first one and ripped the head and did not remove the nail. Second one, I got the nail. Third one, I ripped the head. Fourth one I got the nail. Test is inconclusive. I think the first one I didn't have the paw seated on the nail well enough. It also takes a good shot with the hammer and I was learning that as I went. I'll have to pull some more nails, but I was feeling like there was a little learning curve to it. It may work fine once I do a few more. I may also put the attachment on my other slide hammer which has a heavier hammer. Here's some pics of the tool on my cheap slide hammer.