Out of interest mate did you watch this video?
Does the Rippetoe execution/form look solid to you?
https://www.youtube.com/watch?v=CnBmiBqp-AI
100% disagree with Mark Rippetoe on this particular subject. He's instructing the lifter to use a lot of body movement, he says; "we're going to use a horizontal hip movement with locked knees, to generate a little bounce out of the bottom." This goes against everything I've been taught as a former Olympic weightlifter. The question one needs to ask is this: are we solely interested in moving the bar overhead, or is our aim to mainly work our shoulder muscles? I know very well how to get the weight up overhead in the most efficient way possible, and it has
zero to do with shoulders, and everything to do with glutes and quad strength and power. If your aim is to solely work your shoulder muscles, then it's critical that you eliminate all body movements. Why is that? Because this exercise is called the press, and
not the push-press, or the power-jerk, or anything that has a "drive" connected with it. By "drive", I'm referring to the thrust you generate via the usage of other bodily muscles other than your shoulders, with the purpose of making the exercise easier on the shoulders.
So what is my recommendation for anyone interested in placing maximum focus on his shoulders' muscles, where the shoulders, with their true strength, are the generators of force that would ultimately see the bar above your head? The
only body part/s I should be able to observe moving whilst you're in the process of pressing (and not driving) the bar above your head, are your shoulders and arms.
Get your feet into a modified jerk position, that is to say, feet apart with one leading the other. I say "modified" because the spacing (or distance) between your feet ought to be half (or even less) of that of a proper weightlifting jerk feet stance. Also, your back foot needs to be anchored, and by that I mean heel fully in contact with the ground (unlike when jerking a weight above head with the heel of your back foot being off the ground). A slight bend in both knees is also recommended.
Placing yourself in that position, helps to transform your body from the waist up into one whole unit, with your hips; lower back, and abdominal wall working as one grounded/solid anchor.
Nothing moves here except your arms and shoulders. There's no pushing (not even in the slightest), and there's certainly no driving of the weight off of your shoulder area.
That's a pure and true shoulder press, with more stress on your shoulders and less on your lower back.
Edit: The sport of Olympic weightlifting made the right decision when it removed this particular pressing movement (as described by Mark) from the Olympic weightlifting competition lifts, leaving the current two, namely the snatch and the clean and jerk. Why the removal? Huge stress placed on the lifter's lower back region, causing all sorts of problems.