I personally believe the stiff Jabb is the effect of everything in your body, your whole cns firing appropriately and being ‘tense’ right at the last moment upon impact. You can’t have perfect technique in your arms and shoulders are out, hips are wrong or weight transfer wrong. So as LB said, relax until the end. An unseen Jab feels like a stiff Jab because people just don’t know it’s coming. Learning how to throw it deceptively without any telegraphing is key.
I remember once lobbing punches and kicks at this Islander, bloody hell, nothing effected him then I popped a stiff Jab, not much power in it but it was thrown from the hip and he didn’t see it. It dead stopped him in his tracks as he was coming in on me, he stumbled back and just saved himself from falling… enough to keep me on the assault for the rest of the round.
Just do it over and over, every angle, fast, slow, touch your opponent up. Do it starting, do it finishing, do it as a power punch, do it as a tap just keep doing it. Get your breath right so your diaphragm fills and expands at the right moment. A loose core will render all your punches ineffective and I’m not only talking about strength in your core muscles but strength in your breathing.
Yep. A stiff jab is just a jab with your weight behind it - kind of “vaulting” off that back foot and into the punch. You don’t really land it any differently than a regular jab. For some guys, it IS their regular jab.