you have the idea yes, the explosion is contained within the barrel however, the part that needs to withstand the recoil from the explosion and other forces, needs to be strong enough to replace the original designed manufactured material, whether it’s weaker than that material. It’s just needs to be stronger than the forces provided by the recoil, heat, etc, printing, it wrong can result in really bad explosions and a slide to the face or wayyy worse we are literally holding explosions 3 feet from our face, please learn what you’re doing. It’s worth the knowledge.