Ouh didn't notice your answer.
Well, I tend to warm up with 20 reps with the bar without additional weight on.
Then I just got for the bar+ 10kgs in each sides, ithout any real issues. If i then try to top that with additional 2.5kgs in each side.. It gets hard. Very hard. like a max of 2-3 reps.
I do think that i may need to improve my warm ups.
About my shoulder, it's a pain that i apparently have had for a long time. A year ago, i went to the gym with my friend once, and tried one of the chest machines, and I got the exact same pain as I do now. I have no Idea why though.
And sure, Im gonna have to keep pushing, I have experienced a great deal of improvements in other exercises.