Source: US Justice Department, Office of the Inspector General, Review of ATF’s Project Gunrunner (November 2010), p. 62.
Here’s some more excepts:
There is no federal statute specifically prohibiting firearms trafficking or straw purchases. Consequently, ATF agents and federal prosecutors use other criminal statutes to charge individuals involved in firearms trafficking crimes. These statutes carry relatively low sentences, particularly for straw purchasers of guns. The Sentencing Guidelines also provide short sentences for firearms trafficking-related crimes. As a result, individuals convicted under these statutes generally receive lower penalties than persons convicted of other types of trafficking (pp. 58-59).
According to our analysis of ATF data, the penalties imposed for violations of the four statutes that ATF most frequently used to combat firearms trafficking with Project Gunrunner cases are lower than penalties for violations of statutes on other types of Project Gunrunner cases. The difference is especially acute when compared to penalties imposed for violations with a drug nexus. However, criminal defendants are often charged with criminal statutes that include firearms trafficking offenses and other crimes which carry longer sentences. For drug conspiracy violations, the penalties imposed average almost 10 years. In comparison, although straw purchasing is one of the most frequent methods used to divert guns out of lawful commerce according to ATF, we found defendants convicted of offenses related to only this criminal activity are generally sentenced to less than 1 year in prison (p. 60).
In discussions with the OIG, Department and USAO attorneys explained that proving the elements necessary to obtain convictions under the statutes used to combat firearms trafficking is difficult. For example, a Deputy Assistant Attorney General who was a former AUSA told the OIG that willfully engaging in a firearms business without a license is a very difficult charge to prove because the government has to prove that an individual was acting in a business capacity. To do that, ATF must establish that the sale was not a private transaction but was part of a revenue earning enterprise. In practice, this means ATF must get the suspect to admit or acknowledge selling guns “willfully,” as specified in the statute. According to the Deputy Assistant Attorney General, many suspects can avoid prosecution simply by claiming they were selling guns from their private collection, which is not a crime (p. 64).