Re: punch through
You can perceive it very well on the heavy bag... The "punching through" will make a muffled 'THUD' sound as it pushes the bag around, while the "snapping punch" will make a big 'SMACK' sound as the bag convulse. The pushing punch tends to be slower and tiring, as you uses much more energy on contact. I think the pushing punch is somewhat useless on the head, since the head will bounce around and it won't absorb it's energy, making you tired as you opponent will not be as much damaged, on the other hand, this punch seems to be very effective on the body, especially on the rids, since the body won't bounce around and it won't be able to dissipate it's energy besides breaking itself. The snapping punch on the other hand, is fast, not necessarily weak and super-effective on the head, since there's no waste of energy and it can have enough knockout energy in it. You can drop a opponent with a well landed jab, so don't waste your energy trying to break rocks with your fists and swingin' hay makers around. If you're looking to achieve the snapping punch, you must think of yourself as a whip instead of a bat, it's all about being relaxed and explosive breathing, try not to punch with your shoulder. You must visualize your arm as a rubber band, it must be lightning fast and relaxed as it explodes and you should retract it as soon as you can, so you can minimize the contact time and maximize it's energy dissipation. Boxing is not a brick-breaking competition. Good luck! I wish you the best!