Hot Shot nipples work great for me.This issue is just about always a result of the cap fit to the nipple. Either a new nipple that is slightly oversize for the cap, or a used nipple where the top has mushroomed. If a used nipple that has mushroomed you should replace it. If a new or newer nipple then take the nipple out, chuck it in a drill and run it on a flat file to remove some material. Do a little at a time and check with a cap as you go. Cap should go on with a snug fit but you should feel it bottom out.