If the top of the projectile that you have has either two flat sides (for a wrench) or a hole on the side, near the top (for a spanner wrench) it may be a fused projectile.
Someone with more knowledge than I have will have to tell you if it can be disarmed or not. We were always taught not to screw with these if we ever found them on the ranges. When we shot the .50 cal machine gun, we would set off explosives that littered the ranges. (We were in Korea and used some of the Korean ranges for target practice. They did not use practice rounds, they used live ammo.)
Inside Every Bright Idea Is The 50% Probability Of A Disaster Waiting To Happen.