Cartridge

A cartridge, comprising:

• a case including a first end and a second end;
• a primer disposed in the case at the first end;
• propellant disposed in the case between the primer and the second end;
• and
• a projectile at least partially received in the case at the second end, the projectile including
• a main body with a tip and a tail disposed at opposite ends of the main body, the main body defining a counter-bore extending from the tail toward the tip so as to define a piston axis and a through-bore extending from the tip toward the tail along the piston axis, wherein the counter-bore defines a counter-bore diameter and a counter-bore length and the through-bore defines a through-bore diameter and a through-bore length, the counter-bore diameter not being equal to the through-bore diameter, and
• a piston received in the main body, the piston including a base and a head disposed at opposite ends thereof, the piston also including a shaft with a first portion and a second portion that cooperate to connect the base and the head with one another, wherein the through-bore length is greater than the counter-bore length so that the projectile defines a non-deployed state in which the base is entirely received within the counter-bore, the first portion of the shaft is received in the counter-bore and the second portion of the shaft is received in the through-bore, and the head is received in the through-bore, and a deployed state in which the base is entirely received within the counter-bore, and at least part of the head is not received in the through-bore.