The strain is caused by the explosion of the powder in the round. There really isn't anyway around it. If you are going to accelerate a projectile to speed, th

The strain is caused by the explosion of the powder in the round. There really isn't anyway around it. If you are going to accelerate a projectile to speed, then you are going to get equal but opposite force on the device(per Newton's law of physics). You might be able to print a low speed, low weight projectile item like a b.b. gun.