Breaking defensive lines

Question
Hello Nick, I play as no.8 for my club. im one of the biggest anf fastest guys on the field. I carry the ball alot and make a few yards but not as much as i would like. I want to be able to break tackles and make yards like the likes of ma'a nonu, chabal and lomu. If you could give me any advice that would be great!
Also i was wondering how do you tackle someone but make sure thay dont get up and if they do theyll remember the hit for days to come.
p.s: For an incredible tackle video go onto www.rugbydump.com and find : ma'a nonu absolutely slaughters ben blair
its in big hits and dirty play!
if you find it could you explain to me how yo do it?
cheers Nick

Answer
G'day John,

I will answer the tackling bit first. It is a common question that comes up so if you have gone over my old questions (which I suggest) then it may look similar.

When a player is moving towards you (or vice versa) do not look at their body as a whole, instead focus on the point of center between their hips. Often a coach will tell you to "eyeball" the "string of their shorts". This focus will allow your brain to only register the runner's center of gravity: the "mass" of their torso. No matter what a runner's arms, legs or head does the torso is usually stagnant.

Keep you feet active, stay on your toes either moving towards them or running in place. Close the space between you and the runner swiftly but stay in control. This is to limit the runner's options as much as possible.

Focus on the "string of their pants" and drop your center of gravity to set up the hit. Aim the shoulder to that string. Drive hard though the legs, explosively. The shoulder should snap forward as it hits the body, like a short, sharp punch.  


so summarize:

1. keep the feet active "live"
2. focus on the "string of their pants"
3. drive the shoulder to the "string of their pants", drive hard though the legs, explosively.  

I took a look at the tackle that Nonu did. He basically did the same thing except he lifted his sight/contact line to the center of the chest in an aim to smash the ball out of Blair's grasp in the tackle. You must note that in this case Nonu has the advantage of being a much bigger player than Blair and that Blair was focused on the ball (which was a bit of a "hospital" pass). In this situation Nonu took a calculated risk. If Blair was a similar size and had the ball in hand to focus on a on-coming tackler then Nonu could have been bounced off in the tackle. Nonu is  a good player so in that situation he would probably go for a tackle like the one I describe above.

As for breaking the line. If you look at the tape of the players you mentioned the key factors are:

1. run a line around a player. Pick one side to hit. If you can fake a player to go left or right they will be slightly off balance and you will be able to run through them better. It is not about the big contact or hit. The smart player gains ground and keeps possession buy running through "doorways not walls"

2. Lower your center of gravity as you come into contact. Drop the shoulder.

3. Keep your feet, pump the legs in short aggressive bursts to keep traction, power and stability.

4. Keep your options open, if possible draw the player and look to off load to a team mate. Once the pass is made get into a support position to receive a pass as well.

Let me know if you have any more questions on this.