BJS's firearms used in crime '93-'11 - 478,000 (2011) -- http://www.bjs.gov/content/pub/pdf/fv9311.pdf

There were about 20,000 firearm suicides in the most recent year that the CDC has released numbers (2013) - http://webappa.cdc.gov/sasweb/ncipc/mortrate10_us.html

There were about 84,000 non-fatal firearm injuries in that same year-- http://webappa.cdc.gov/sasweb/ncipc/nfirates2001.html

How many guns are there in the US? Well, since 1998 when NICS came on line, there have been background checks for over 220,000,000 transactions. https://www.fbi.gov/about-us/cjis/nics/reports/nics_firearm_checks_-_month_year.pdf For clarity sake, let's assume 1 check = 1 firearm. If we assume a firearm has a typical lifetime of 25 years, and the number of checks is somewhat representative, then in the last 25 years, there would have been another 50-80 million firearms changing hands. So the total number of guns is somewhere between 270,000,000 and 300,000,000. Let's use the middle at 285,000,000.

How many firearm owners are there? That's where it gets tricky. Self-reported numbers vary. Gallup puts the percentage at 41% - http://www.gallup.com/poll/1645/guns.aspx, households number at about 123,000,000 ( http://www.statista.com/statistics/183635/number-of-households-in-the-us/ ) and the population is about 318 million (https://www.google.com/publicdata/explore?ds=kf7tgg1uo9ude_&met_y=population&idim=country:US&hl=en&dl=en). Looks to be about 130,000,000 gun owners or 50,000,000 households.

Okay, given those numbers, the odds of any gun being used in a crime, suicide, or non-fatal injury are 582,000 / 285,000,000 or 0.21%. The odds of any gun owner being involved in any of the above (assuming even distribution, which is silly) is 582,000 / 130,000,000 or 0.45%.

So 99.79% of guns will not be used in any gun crime, suicide, or non-fatal firearm injury and 99.55% of gun owners will not be involved in any gun crime, suicide, or non-fatal firearm injury.

The thing about a 'ballistic fingerprint' is that unlike the fingerprints on our hands, 'ballistic fingerprints' change with use of the firearm and cleaning. Fire 500 rounds of ammunition in an afternoon through a handgun, and the 'fingerprint' will have changed.

They're completely destroyed by replacing the barrel on the gun (a 5 minute procedure for many guns), something that many gun owners do to increase precision or to reduce wear and tear (like changing tires on a car.)

Matching a casing to a gun works when you find a freshly used gun on a suspect, and you have casings recently fired from it to compare to. With any length of use between the first point and the second, the 'fingerprint' match becomes inconclusive. Imagine a 'tire fingerprint' on your car as it rolls off the lot, and compare to the 'tire fingerprint' after 30,000 miles-- or after you get a new set of tires from Pep Boys.

The whole CSI / NCIS / Law & Order slew of tv shows have given folks an unrealistic expectation for the science of criminal forensics.