this can be a major issue. guns off the street is good. but imprisoning innocent people - which will most likely be the case, is not good.
the underground gun market is very unscrupulous, as one would expect. people use guns for whatever they need to, then sell them to get rid of the evidence. there are three types of guns. legal, or registered guns, which one gets with a permit from a gun shop. there are "clean" guns, which people buy at under the table/with false ID at a gun shop or internationally, file off the serial, then sell it. then there are "dirty" guns, which start off as either of the first two, but become dirty when they are used for a crime. most guns you find on the street now, are dirty guns. clean and unregistered guns are much too expensive for inner city kids to get a hold of.
so picture this. you buy some shit, half-falling apart junk gun for cheap for personal protection. the cops find it, and when run the ballistics test, they find out that the particular gun is responsible for a number of shootings and murders in your neighborhood. you didnt do it, but you were in possesion of the same gun that was used to murder Xnumber of people. you're a black street kid with a shit education and low income. you cant afford a lawyer, so you have two options: rat on the guy that sold you the guns (which will most likely get you killed or at least crippled), or go to prison for all the murders - possesion of the murder weapon is more than enough for a conviction if you got a shit lawyer and powerfull prosecutor. and to most cops....a black kid with a gun belongs in prison, regardless of circumstances. although they might not bust kids for weed, they will definitely not even bother siding with the kid if he's found in possesion of a murder weapon, weather innocent or not.