First of all, that not training round, from where this idea comes from ?? At least not from the military. Maybe the civilian call them training round, but that's weird. This is an anti-rioting PVC or rubber bullet. Since the army, at least in Canada and USA, don't use them for training, I don't know why you called them "training" bullet
2nd, this thing can only fit in caliber 12 gauge firearm, that mean shotgun or specialized anti-rioting weapon. Believe, I never saw an adaptor in our C1 and C2 stock for that... This is the bullet, this thing is insert in a 12 gauge standart bullet, so the entire round look like this...
3rd, I can't understand why you say that this thing can kill, it's ridiculous, it got an average speed of 100-180m/sec, very slow compared to rifle or pistol bullet,no punch, big (about 24mm diameter)
Believe me, thoses things are non-lethal...