Was: Aluminum cutting Re: Gunsmith, off topic

> Yes, I am...among other things.

You couldn't explain how a gas blow back bolt actually works for me could
you? How is the gas used to cock the bolt back after a bullet is fired in
things like the MP5 rolling bolt? For a bolt to be called closed operation
does it have to turn 90 or more degrees to lock? Does the gas ever go to a
resevoir in these kind of bolts for consistancy or by gas does it just mean
the recoil from the bullet firing pushing the bolt back? This is my little
brother who has forced me to ask you because he can't find it in his Jane's
guide. When they make things like the chamber of a gun what kind of accuracy
are the best made to?

Thanks for any help,
John