There's no unmodified pump gun these will work in with complete reliability.
Some guns can be modified to operate with them, but this prevents using standard length shells in the gun.
Some people have had fairly reliable operation in some guns, but not enough to trust your life to them.
They'll work just great then suddenly you have a stoppage like a shell turning over backward in the action causing a serious jam or some other sort of mis-feed.
These work well in single and double guns but not in a pump and certainly not in an auto.