Stone bows or pellet bows, whatever you want to call them.  I need some answers, if anyone can field them.
  Firstly... in a regular stone/pellet bow, (not the crossbow type), how do you keep your fingers from being blasted by high speed pebble?
  Secondly... are there any simple locks for crossbow-type stone bows?  I've seen lots of complex metal ones, but no simple ones.  I have thought of a design myself, but I haven't tried it out yet.

I have a bow string I put a pouch in the center of and sometimes use on my 65# compound bow i usaly fire one ounce egg sinkers out of it. And so far have never hit my finger's the truth is
I never thought about the possibillit till now

A primitive stone bow is just a long bow that has a pouch for shooting pebbles.  They are used extensively across Asia, some parts of Africa and even South America.  In China, they developed into crossbow pellet bows, for shooting birds.  These designs were then carried back to Europe where they were very extensively used for hunting.  Italy was first to use them in Europe, but they spread and became quite popular.  In England, they were used until about the 19th century when guns became cheaper, and were used for shooting lead bullets.
  I have used a regular pellet bow before, and it whipped the stone hard across my knuckles.  Not nice.  I was wondering whether a twist of the hand is needed to avoid the pellet.

Nah, that would screw up accuracy.  Plus, the way you hold the bow would be different with the handle lower down, and so the stone or pellet would actually go through the same point, by your hand.

That's probably why the Chinese made them into pellet crossbows.

I have been thinking about pellet bows quite a lot recently - I was thinking about the possibility of a crossbow that could shoot both pellets and bolts, for in tough corners when you have run out of bolts.

For a simple pellet bow, I have no doubt you could just use two different strings.  But the crossbow would be slightly different - stringing and restringing would be more difficult.  I guess you could use one string, but it would have to be well designed.

The hurt of the pellet hitting your hand is not so bad - it's the fact that the pellet is not going to hit anything if it has already hit your hand, making the weapon a bit pointless.