Most probably is lack of technique. Underwater is a litlle easier. But the main is, brace yourself for the pull and do it in one go. I like to present my gun to inexperience strong people just to afterwards show off my skills. Even after they see how i do it, they still fail, because they try to do in one quick go, but without preparing to close the elbows until the end so they came up with the wishbone almost near the shaks fin's position, but from there they can't pull the rest. I is a kind of the weightlifting snatch. Do go pulling it, just pull it,