I will use these at work where the metal thickness is no greater than 1/8 inch. I use a battery operated impact driver and I have noticed that they break easily after about 15 uses. If you need speed they are just okay, but I have also learned to drill a pilot hole, then run the tap/drill job into the pilot. I find their best uses are for making machine guards, but after that they mostly a pain as they will break easily. I would not recommend them for gun work.