equal and opposite reaction.....mass of a astronaut in a space suit is very much more than the mass of a bullet. while the numbers at the muzzle are equal in both directions, it is mitigated considerably by this difference.
shot the sun..in orbit you are traveling around the earth (actually falling to wards it) at around 18500 mph. this forward velocity allows you to miss the earth by the same amount you are above it, thus maintaining your orbital position. adding 500 or so mph (velocity of a handgun bullet) to this speed will not boost the bullet out of orbit. need 25,000 mph for that. it will get it to a higher orbit.