Reply #101: Ok...want anecdotal evidence? [View All]

[DoNotRefill]

IIRC, both NY and Maryland currently require mandatory ballistic fingerprinting. Would you care to estimate how much their systems have cost so far, and how many crimes have been solved because if it?

"Ballistic fingerprinting" is a misnomer. Tool and die marks are NOT fingerprints. As I'm sure you're aware, fingerprints can't really be altered. If you get second degree burns on your fingertips, after you've healed, your fingerprints will still be the same. You can alter them in some ways (for example, sanding them with extremely fine sandpaper will remove the ridges for as long as it takes to wear off the rest of that layer of skin, but then they come right back. You can also mutilate them, for example if you slice them with a razor blad repeatedly and relatively deeply, so that scar tissue displaces the fingerprint), but just in the course of "normal wear and tear" you're not going to change your fingerprints. That's why they're so good for identification. Now "ballistic fingerprinting" isn't the same at all. EVERY round fired through the barrel of a gun removes some of the tool and die markings that comprise the quote ballistic fingerprint unquote. If you fire 100 round rapidly through a single gun, the heat retained by the barrel will cause the metal to expand and soften a little bit. Repeated rounds will quickly erode the microscopic tool and die marks that comprise "ballistic fingerprinting", and heat retention in the barrel itself will cause the barrel to expand. Consequently, a bullet fired through a "cold" gun will have a significantly different ballistic fingerprint than the last bullet fired seconds later from the same magazine in the same gun. Even if the gun is not fired repeatedly in a short time, each bullet passing through the bore will remove microscopic bits of the tool and die marks, which naturally obliterates the "fingerprint".

You're familiar with the concept of a worn barrel, yes? Repeated firing of the gun wears a barrel out. This can happen quickly or slowly, depending on a wide variety of factors (which include but are not limited to the composition of the bullet jacket, the case capacity, the propellant used, and the caliber of the firearm itself.) I've got guns that have not yet worn out their barrels after 100,000+ rounds downrange (a high-quality .22 target rifle) and other guns that need to have their barrels replaced on average every three hundred rounds fired to maintain accuracy (which is decreased by barrel erosion). On the gun that's had more than 100,000 rounds through the current barrel, the microscopic imperfections that comprise a "ballistic fingerprint" have long since worn away. On the gun that has the 300 round barrel life, each bullet significantly wears away those imperfections too (which is why it has such a short barrel life).

Now all of this is predicated upon no negligence or deliberate activity to alter the ballistic fingerprint. If there IS negligence or a deliberate attempt to alter the B.F., all bets are off. Why? Because mandatory ballistic fingerprinting is dependent upon the gun not being used much, and upon there being no change to the barrel. The gun is "fingerprinted" when it's new, and then it goes on it's way. Once the gun is in the end-user's hands, all kinds of things can affect the ballistic fingerprint. Rust will alter a B.F. almost immediately. And we're not talking about massive rust...we're talking very shallow surface rust, which is called "frosting" because it looks like frost crystals formed on a windowpane. Massive rust, which involves "pitting", or very small holes in the metal, is even more damaging. Then you get into other factors, such as the type of projectiles used. For example, if you use Full Metal Jacketed rounds, the hardness of the jacket wears away the tool and die marks rapidly. If you use plain-jane lead rounds, lead "fouling" (which is tiny bits of lead that are melted by both friction and the heat generated by the propellant) will fill in the little gaps that is what tool and die markings are. Then you get into cleaning the gun. If the gun is not cleaned, the dirt, debris, and various forms of fouling will fill in the tool and die marks, because they give the substances a place to attach themselves to. If you DO clean the barrel, you are cleaning it with chemicals and abrasives which are there to scrub out the fouling, and also erode the tool and die marks. Additionally, cleaning involves the use of "bore brushes", which are metal (normally either copper or stainless steel) and which microscopically scrape the barrel, which both obliterates old tool and die markings and installs new tool and die marking (in the form of microscopic scratches....for a demonstration of this, get a piece of stainless steel like a knife and scrape it across a cooking pot hard. You'll normally get visible scratches. Same process, different scale.) Then you get into things like firelapping, which is a process used to remove barrel imperfections to improve accuracy, and cryogenic barrel freezing, which is another accurizing process that alters the ballistic fingerprint by re-aligning the molecular structure of the metal in the barrel by application of extreme cold. Please keep in mind, that all of this stuff is natural, and isn't used to deliberately defeat the BF systems.

Defeating the BF systems is virtual childs play. It can be accomplished in almost infinite ways. Examples of this would be to deliberately scrape the bullet up before loading it, so that additional markings were put there, or modifying either the barrel throat or muzzle crown with something as simple as a rock or piece of steel to scrape it. A chamber brush (which is a brush used to clean the chamber, and is quite common and cheap) alone would work on the throat, and almost anything at all would work on the muzzle crown (I've seen a LOT of muzzle crown damage over the years caused, strangely enough, by people using their handguns as a hammer). Remember, under a mandatory system, people are not continually submitting bullets to update the BF, it's done once when the gun is new, and then never again unless there's a match.

Anyway, I've ranted for quite a while here, and am about to call it a night. I will, of course, check the thread later to answer any specific questions you may have. The "biggie" to remember, though, is that human fingerprints generally don't change that much, while "ballistic fingerprints" change tremendously, for a wide variety of reasons, both innocent and indicative of an evil "mens rea".