Well to solve the final question about getting more arrow speed!!! I have now solved the problem. What I have done
is slide a smaller carbon tube ( from a fishing rod) 
inside the bolt of a crossbow bolt!!!!!. This carbon tube was sealed on one end..... 
Next I had a small lighter valve glued on the end of the tube and this sticks out the end of the bolt just enough to open up when the bolt is shot out of the crossbow!!!! 
The tube is filled with compressed gas!!!!! 
Now these have to be filled before you go out to the hunting areas. When you load the gas charged bolt in or on your crossbow be carefull not to put it in too hard or you will release the gas and lose the full power effect....
When you shoot this arrow as the string is released it will not only push the arrow down the rail at it's regular speed but simultaneously it will trigger the end of the gas valve releasing the pressure and projecting the bolt much faster than you can imagine thus giving you much more needed speed to shoot a deer that jumps the string!!!! 
Here is the trick. send $199.99 plus shipping and taxes and the extra cost of my brain power and I will throw in for free ( yes for free!!!) a free bottle of my very own home brewed gas that will surely help you knock down anything in it's path!!!!! send it in the next few minutes and I will laugh even more!!!!
