A soldier's salary is his monthly pay as determined by time in service, time in grade, and current pay grade. See the related question and the link there for the current US Military pay scale.
Military pay is determined by rank, time in grade, MOS, and years served.
There are many things that go into determining what your pay grade should be. This is different for many people.
Pay is determined by rank, time in grade, and other factors.
Pay is determined by rank/corresponding pay grade and time in service.
Pay is determined by pay grade and time in service, not by MOS.
Number of things to consider here. First, you didn't say which military. Secondly, pay is determined by rank and corresponding pay grade - not by occupation. In the US military, it's a matter of rank (plus corresponding pay grade), time in service, and additional allowances (e.g., housing allowances, hazardous duty pay, etc.). So, an E5 in the Marine Corps serving as a sniper will have the same base pay as an E5 in the Air Force serving as some sort of desk clerk.
The pay grade GS3 refers to civilian government workers; it is not a military pay grade. There is no pay grade "G3."If you are referring to the military pay grade E-3, this is the equivalent rank of a Private First Class (PFC) in the US Army, a Lance Corporal in the US Marine Corps, an Airman First Class in the US Air Force, and a Seaman E-3 in the US Navy.
The highest enlisted pay grade for all US Military services is E-9. The the link below for DoD Pay Chart.
All US Military pay is determined by rank and the years of service. Military snipers are paid by their rank and pay grade in the military service. To best answer your question, anywhere from $16,800 to $50,000 a year depending on several things. No they don't get paid by kills, and they don't do contract work. There is no bonus for being a sniper.
See related link 'US Military Basic Pay Chart 2010 - Commissioned Officers' at the bottom.
Yes, there are pay differences based on the branch of the US military you enlist into. Each branch has its own pay scale and salary structure. However, the basic pay is determined by rank and years of service, so individuals with the same rank and years of service will generally receive the same pay regardless of branch.