Generally, they work better if you glue in more than one "cap". But, you have to take your time, and most folks just don't have the patience for that kind of work. The caps are black powder charges, while modern percussion caps use a different chemical compound that is more sensitive to impact. You have to clean off the top of the nipple after each shot, AND, you have to use a gun where the hammer strikes a new nipple squarely, to insure reliable firing of these home-brewed caps.
If you are using an old nipple, or if you have never square the face of the hammer to the top of the nipple, ( resulting in the hammer hitting on one side of the nipple or another, but not squarely on the whole nipple), you can have problems. They do not produce the same quality or quantity of flame with caps, as a modern percussion cap makes. So, I would not advise using them with the Substitute powders, which have higher ignition temperatures than Black Powder. :thumbsup: