The criminal charge of robbery is actually something different than what most people expect. In most states, in order to be charged with robbery, there must a victim present at the scene of the crime, as opposed to a burglary charge, which does not require that a victim be physically present at the scene of the crime.
As you can see in the this news story about a gun story burglary, the crime is being called a robbery. Burglary, in most jurisdictions, is a felony because it involves not just a theft, but also, unlawful entry onto another's property. So in the above gun store burglary, it is likely the defendants would face felony charges if caught.
Robbery Is a Wobbler of Degrees
Like most theft or larceny crimes, in most jurisdictions, robbery is a wobbler, meaning it can be charged as a misdemeanor or a felony depending on the circumstances. If there was no force used, and there are no additional charges or enhancements, the value of the pilfered item(s) will determine the severity of the charge. Additionally, many jurisdiction have degrees of robbery that provide certain robbery offenses, and repeat offenders, with harsher penalties.
If a person is facing petty robbery charges, or misdemeanor robbery charges, the penalty, at worst, will be one year in jail plus fines and restitution. If the charge is a felony, with additional charges and/or enhancements, a person could be looking at several years behind bars, plus even more fines as well as restitution.
Robbing a gun store is likely to wind up in felony territory as not only are guns expensive, but it is unlikely that a gun store could be robbed without the robber being armed.
Robbery Can Be Enhanced
While robbery has a few different degrees that can be charged, it can be subject to add-on charges and enhancements. If there is force used in the commission of the robbery, frequently it will be charged as a felony and called aggravated robbery. If a weapon was used, robbery will more than likely be charged as felony and called armed robbery. Additionally, if a weapon is used, or other crimes were committed, such as breaking and entering, there may be additional add-on charges.