Abstract: A system includes an incomplete cartridge for a firearm and a field-selectable capsule for the cartridge. The capsule contains a product that may tag a person for tracing, induce sleep, cause disease, or have other effects. Capsules are preferably removably adhered to a strip with each strip of capsules potentially serving a different purpose. The incomplete cartridge includes a bullet that has an opening at the payload end. The opening receives and retains a capsule upon insertion. The capsule is made of a frangible material that releases the product upon impact. The capsule may be formed with a snap-in ridge extending from its exterior wall, which snaps into a complementary recess in the bullet opening. Alternatively, the capsule may be coated with a contact adhesive so that it sticks to the bullet wall defining the opening. A peel-off covering atop the strip shields the contact adhesive from contamination.