Try this on your flat bench, but the technique is focusing on all pec. Going for 4 reps at 305 has to involve your arm and delt strength a lot moreso, and although heavy on the pecs does work, your pecs definitely do not become the primary focus when working with a real heavy weight relative to your own strength. Tee mind cannot focus strictly on pec while using super heavy weight. The focus shifts to the arms because of the heavy load.
Using some lighter weight, while emphasizing the pecs exclusively, will result in better development in size. Trust me on this, if you do higher reps and mentally focus exclusively on the pectorals pushing the weight, you will grow the chest.
Also, the movement isn't rep and pause. Keep constant tension on your chest. Do not complete a rep and hold the bar at the top for any amount of time, the bar hits it's height and immediately goes into the next rep without stopping while keeping the bar controlled. You WILL hit failure very fast doing constant tension method, so careful on how heavy you go. That's why my suggestions will reflect that.
I also can do 305 for 4, and even 5, but this last month I have not done one rep over 225lbs and my chest has GROWN and developed more than the previous 2 months using heavy weight. I didn't put your weight that low(225) to start with, but give this a whirl. I am assuming you are going to hit in the 16-18 reps your first set. That's what we are looking for with constant tension. You should get super pumped, and your chest will hurt like a son of a bitch the next day.
Remeber, the mental focus is this: When you are under the bar, the mind is focusing on the chest. The chest needs to do EVERYTHING. All the arms do is hold the bar. Your arms do not press the bar up, the chest contracts inward to make the arms extend the bar raises as a result of this. That's how you have to think of it.
You can also uses a slightly more narrow grip too, which allows for greater contraction.
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Ok so my chest is lacking, I can lift a fair amount but my pecs don't really look like the rest of my body. I have been working out seriously for a 6 years! I'm 29, 6'3, 245 so here's my routine, anyone that wants to critique feel free!!
Flat Bench
Warm up - However you want to go.
Sets 6
255 x Failure = (maximum reps)
255 x Failure
235 x Failure
225 x Failure
205 x Failure
185 x Failure
Incline Flyes
4 Sets ( I go light with high reps)
70 x 16 - 20
80 x 15
70 x 16 - 20 then drop immediately
65 x failure
Incline Dumbbell
4 Sets
90's x 8-10
110's x 8
120 x 8
130 to failure (130 is as high as my gym has)
Cable Crossovers
3 sets
90 x 12
100 x 12
110 x 12
Every other week I throw in decline.
My chest feels fatigued after I do this but I'm not really seeing results. Am I doing enough??
Cable Crossovers
The amount of work you have been doing is enough work. I would do flys after all of your pressing work is done. Try the constant tension method I suggested just one time. If you did really focus the work in the pecs, you will be really sore. Plus it's a fresh routine which in and of itself gives results as long as you go hard.