The long boom grapnels with thick wire grab the best. Think of it acting in the same manner as an anchor chain in ski boating.
Ants, the tighter you keep your line while sliding the better, it helps the slide clip to move towards your O ring stopper a lot easier, it also lessens the chance of your slide trace from wrapping aroung your main line. This will definately result in a burn off. Another very important trick to consider is to ensure that your slide get all the way to your O ring by shaking your rod until you are confident it has reached its O ring.
If however you get a pick up before the slide is at the O ring. DO NOT STRIKE. It will result in a burn off. Simply lower your rod to face your line entering the water and wind your line in. Invariably you will feel the line get very 'heavy', and thus know that the slide clip has reached the O ring. I hope this helps
dont worry about your grapnel when you do get a pull, because the fish is pulling the line at a different angle, the sinker come away from the sand easily.