These are non magnetic, and can be used at your indoor range.
Not magnetic, but do check with your range rules. Some won’t let you shoot anything but frangible rounds.
No they are not magnetic, you should be able to use these indoors but always check with the range before shooting because each range have their own set of rules and regulations. In my area one will let you shoot only birdshots and the other one only allows slugs out of your shotgun