im very intrested in projectile based weaponry and i was wondering when the hammer hits the back of the primer on the

Question: im very intrested in projectile based weaponry and i was wondering when the hammer hits the back of the primer on the shell and the gun powder ignites, then the gunpowder explodes releasing gases into the barrel. what do the gases in the barrel do?
- Keywords:
  barrel,
  gunpowder,
  hammer,
  powder,
  primer,
  projectile,
  shell,
  weaponry
Asked by james68 to Ailsa, Evan, James on 23 Jun 2011.
- Evan Keane answered on 23 Jun 2011:
  
  Woah! It sounds like you are an expert. I am not a weapons expert but my guess is that the gas expands and therefore pushes something – probably a bullet in this case you mention. Heating gases so that they expand so that they push something is an idea used in lots of mechanical things – like engines, where you ignite with spark plugs and a similar scenario occurs but the expansion of the gas is used to turn something in that case.
- James Hargreaves answered on 23 Jun 2011:
  
  I think Evan has answered this perfectly!
  I have no idea about weapons i’m afraid!! 🙁

Question: im very intrested in projectile based weaponry and i was wondering when the hammer hits the back of the primer on the shell and the gun powder ignites, then the gunpowder explodes releasing gases into the barrel. what do the gases in the barrel do?