A couple of thoughts on your problem:
1. 275 grain is a bit light for a 9wt, but you indicatged it loaded the rod ok. I use a minimum of a 300, but generally a 350gr on a 9wt.
2. Short heads tend to dump, which gives you the "L" or the rubbish pile at the end. Try slowing down your forward cast. Heads generate a lot of line speed and shorter ones plain run out of unfurling with a kick at the end.
I find that using 26ft Rio Striper heads, I need to slow down the forward stroke to fully turnover and extend the head in a straight line.
Bjoth Rio and SA have debuted heads with T-14 that can be cut to length/grains based on the size of rod. I use 30ft on a 10wt, which translates into 420 grains.