Hawk,
Liquid Nails will work. F26 construction adhesive will work better and it is waterproof. Anyone that messes with 3D ranges is aware of using Liquid Nails. F26 Construction Adhesive is available at lumber yards and Home Depot type stores. It is made by Leach. Clean the surfaces of loose material, make sure it is dry, spread the adhesive and hold it together. You will need to clamp it, say with a ratchet strap. It comes in a tube like toothpaste for small jobs and in a caulk gun tube for bigger jobs. It is good stuff. You can even glue things like bricks. Another great product is the E6001 product made by Willamette Valley Company. The same people that make the Shoe Goo adhesive. E6000 if for indoors and E6001 is for outdoors. Both are a silicone adhesive that will have some slight flexibility which may work well for a target.
All good products, Liquid Nails is cheap and well known. You just saw where Larry Jim Bob from Maine rebuilt his javelina 15 years ago. Man, that must be a hardy strain of javelina to live in Maine ---LOL!
Billy