Im not sure if anyone noticed but Lockon had the advantage at the beginning. He had range to snipe Graham, missed 3 to 4 times as well. Its not like Graham just jumped out of nowhere, and pounced on lockon. If you watch the episode again Graham had to intercept Dynames within Lockon sniping range while still being under fire at far distance.
Yeah Lockon missed the first time, he gave the I was being half @$$ed response, and said in the lines I wont miss again, well we all know what happened the second third and fourth shot.