Mr. Luddite wrote:
On 11/7/2017 5:18 PM, Keyser Soze wrote:
On 11/7/17 5:10 PM, Mr. Luddite wrote:
On 11/7/2017 1:57 PM, Bill wrote:
wrote:
On Tue, 7 Nov 2017 12:38:18 -0500, "Mr. Luddite"
wrote:


Watching a press conference by law enforcement officials
investigating
the Texas church shootings.

They just said that a number of expended rounds have been
recovered that
will be sent somewhere that maintains a ballistics database to
see if
the rifle used had been previously used in any other shootings or
crimes.

So, contrary to some of the discussions we've had here in the
past, it
seems there *is* a data base maintained of the unique markings on
the
rounds fired from a particular firearm.

My only question about this is how "unique" they actually are and how
consistent they stay over the life of the barrel.
If you understand anything about bore erosion, you have to question
the ID of a bullet from a new barrel compared to one 1000 rounds down
the road.
I am seeing a lot of discussion these days about the flaws in the
"science" of forensics.
I would also like to see someone comparing the bullets fired from 2
barrels made consecutively with the same rifling tools. Either the
"science" of striations is flawed or the "science" of tool forensics
is flawed.
I would agree that comparing bullets fired from a particular gun
fairly close together in the life of the barrel might be significant
but most of the "uniqueness" would be from the usage, not the
machining. It is valuable when they find a gun that was tested
shortly
after the murder but comparing a bullet from the new gun to one from
1000 rounds later is more troubling.


I think they are comparing casings, not bullets.



They are. The first report was "spent rounds" but was corrected
later to casings. Harry's comment makes sense. They are comparing
the casing to others found at crime scenes, not from the manufacturer.



Until recently, if you bought a new firearm in Maryland, the shipping
or product box had to include from the manufacturer a spent shell
casing in an envelope that was sent to the Maryland State Police. The
rumor is the Staties here have many 55-gallon barrels full of spent
shell casings from the sale of tens of thousands of new firearms over
the years. Apparently no one ever bothered to compare those casings
with the casings found at crime scenes. In any event, the state of
Maryland has stopped collecting the shell casings.

It's really a corollary of the 10-round magazine limitation. You
can't buy larger mags in Maryland, but you can drive over to Virginia
or any other state where higher cap mags are legal, buy as many as
you want, drive back into Maryland and use them legally.

I would like to see a ban on the sale and possession of bump stocks.
They serve no useful purpose for hunting or for self defense or for
competition.


Every new handgun and rifle that I have purchased in Massachusetts
included a small envelope containing a spent casing from the gun. I
never knew why the manufacturer provided it because we are not
required to do anything with it. I figured it was just proof that the
gun had been test fired or something. I haven't purchased a gun in
about 3 years so I don't know if they still include the spent casing.



Firearm manufacturers do "proof" testing and the casings are likely from
that. They fire a round that is loaded about 50% hotter than spec
through each gun to test the components for durability. I've seen this
firsthand and there are people who do nothing but fire guns all day long.