Wow! Whole lot of chatter in here... So let's clarify: it isn't supposed to pass in a powerlifting competition, and I don't believe I ever indicated that. So hopefully that clears that up.
Moving on: if you really think you can bounce a heavily loaded bar off your chest you might want to rethink it. Your ribcage, while resilient and meant to protect the inner organs, isn't a damn spring. You guys have fallen to the myth that 'bouncing' is responsible for the weight moving upward. I really wish you'd had more respect and asked questions before posting. Specifically you, Cmart.
What you're seeing is called stretch reflex, or the stretch-shortening cycle (SSC). If you're not familiar with it: when a muscle gets taken "too far" out of it's comfort zone, too quickly, the muscle will respond with a quick, involuntary shortening of the fibers. In other words, it'll act like a rubber band being stretched to a certain point and letting go. Healthy tendons are a plus when using this type of training. I'm sure most of you use plyometrics in your fight training; this is just an example of that for the chest muscles.
So hopefully that clears that up. It isn't being bounced off the chest, that's an absurd notion. It's being propelled partially involuntarily by the muscles and tendons of the anterior shoulder and pec major because of the SSC. Make sense? When used correctly it's a formidable tool, and one I hope you can learn to understand and apply. I'm not dogging you for thinking of it as 'chest bounce' because that's what you've heard it called by people who don't know the mechanics of the lift. Now you know.
On to the "this doesn't look like good technique" comments. This form is the best for injury prevention at the shoulder joint (the most common injury for heavy benchers), and maximal power development. If you want to body build, this isn't the bench form for you. I really wish I didn't have to take so much time addressing these comments and could instead focus on talking you through a correct lift. I guess I'll do that at the end of the post.
Anyway, lets address the god-awful(!) 'ass off the bench'. Essentially you're saying that since your high school football coach told you that the lift doesn't count unless your ass stays on the bench that you're holding that as dogma. The mistake behind this is 1) did they know what they were doing in the first place, and 2) could thinking have possibly progressed?
Here's what you're seeing: leg drive in a competitive powerlifter/bench specialist can add up to 20%. That's a big number, and one you'd be foolish to do without in your training. Everyone, at one time or another while benching, has felt their ass lift off the bench when negotiating a heavy or near max weight. It does this because hopefully you used leg drive, which starts the hips driving up, and then they continue up because your body is attempting to put you at more acute angle to the bars path of travel. In other words, turn it into a decline press. During a decline press you can access the more dominant fibers of your lower pec (ever notice how there's more tissue at the bottom of your pec than the top? More muscle fibers.). So you started with the leg drive to accelerate the bar, then continued by putting yourself in a more biomechanically advantageous position.
So, to take it to the extreme: no, you probably shouldn't have your ass two feet off the bench to get that max single. I've done it, I've seen it, you probably have too. If the weight's THAT heavy you can bet you're doing some fucked up shit with your elbows and shoulders, too. In other words, if you're ass comes off the bench and STAYS OFF THE BENCH to the finish of the lift, not so good...So back off the weights a bit.
But if you are aggressive enough with your leg drive that your ass comes off the bench for a split second because you've now correctly turned the bench into more of a total body lift, well done. You've now utilized leg drive fully. The ass stays on the bench in strict powerlifting meets, other than that, USE THE LEG DRIVE. Your body is trying to tell you how to get the most use out of it, listen to it. And drop the dogma handed down by powerlifting trained coaches who, again, don't get the mechanics of the lift. Makes sense?
Did I forget any other objections? If so, by all means let me know. I so love taking my time to put out the small fires of people so insecure that they need to point out the flaws in something they don't know too much about, simply because they feel threatened. If you feel that this applies to you...it probably does.
To answer the questions that WERE posted:
1. Do you have problems sliding across the bench when leg driving? This has been a big problem for me.
--If you have a decent arch, you can usually avoid most slippage. You make a great point, though. With sufficient leg drive and an INsufficient foundation, your legs will push your body backwards. The way I've been able to address this is to try to find a bench where the (p)leather is naturally more sticky or try to chalk up your upper back. Another great trick, if your gym allows it, is just pick up some Stick-um (spray adhesive) and spray the bench before you lift. All of a sudden, you're not going ANYwhere... But, ideally, you'll have your scapula tucked back and under you enough that any leg drive only serves to send the bar up, and not you back.
2. What are your thoughts on the Westside "straight line" vs. the ****l Milita "push towards dick, throw at face" techniques?
--I've found that the best way to make gains without using a bench shirt is to use mostly the MM stuff (they didn't invent it, of course, just popularized it). I'll explain this more when I do a walk-through below.
3. Grip width?
--Depends. I've learned that your body will adapt well to almost any grip you take. I use a very narrow grip for two reasons: I have no intention of using a bench shirt with any regularity (where you'd want a wide grip). And the further the angle of your humerus (upper arm) to your body, the greater the stretch reflex. So grabbing a closer grip means you have to move the bar a little further, but it also means your elbows go further toward the ground, so the stretch on the pecs and front delts is greater, leading to a bigger SSC. Only do this if you're confident in your ability to keep your scapula pinched and you have relatively healthy shoulders.
You know what? I'm kind of put off by the attitude in this thread so far. I'm also tired, and tired of typing. I'm going to bed now, I'll check in the morning or sometime tomorrow. I hope you guys have taken the time to read, and learn. I'm not writing this shit for my own amusement, I'm trying to help you guys out. If you have more questions about the points covered so far, ask. But do so in a respectful manner, please.
Tomorrow I'll write up the walk-though for the movement.