lol, first your problem is reading. I said if not OLP, why not Break Through, Secondly, if a Demo is consistently going to one spot, that means nobody is capping or moving and it's just a farm fest, or that demo is terrible and only Shock strike sniping which is accomplishing very little. Either way, someone going to the same spot every time is an easy kill because you will know where they are.
Thirdly, why are you out to kill the demo if your so under geared? Your goal is to chase the demo and support your front line during a push. Just chasing the demo away is accomplishing something because you limit them to instants while kiting and wasting their cc's on you, while your group remains safe from him bombing them.
If your mad your not getting immediate kills with low pvp levels and gear, why did you roll a class which is extremely gear dependent such as a tank? If your mad about casters, roll a ranger or sin, who are extremely good at killing cloth and light armor and have a much lower gear threshold to do so, these two classes eliminate a cloth's pvp level or gear because they CAN kill them in 2-3 shots. My blue geared ranger has only 230.4 dps - TTS and Pen Shot still hits a PvP 8+ cloth for 2-3k, using a snake tongue I bought for 1 gold.