People often believe what they see on police TV dramas.
Bullets do indeed aquire unique styrations as they pass through a gun barrel... however bullets also tend to aquire "other markings" as they follow their path through space an other objects that they encounter
that tend to distort or completely obliterate these unique markings.
unjacketed lead bullets especially.
The general unique-ness of rifling marks is greatly over-rate when advanced manufacturing techniques such as automated "Hammer-forging" is used to produce barrels (the barrels are literally formed by a multiple hammer forging machine that beats a tube down around a carbide mandrel)
It is ignore by police drama script writers that "ballistic evidence" either comes from excluding a particular firearm OR examination of the shell casing.
as far as tracing Burned DVD's to a particular source?
I know that they can be traced to a particular DVD-Burner, however as there is no national (or international) database of DVD burners they'd have to have a strong enough suspicion with supporting evidence
to get a search warrant and seize your computers and burners to tie their "suspect disc" to your particular burner.
The task would be not unlike finding a war grave and tracing that soldier's death to a particular rifle used in the war he died in.
Unless they strongly suspect that his death was "Friendly fire" and had a strong suspicion that someone in his own unit killed the fellow they'd generally have too many places to look to have more than "Bob Hope or No Hope" of finding the weapon used to do the deed...
THE first thing government security people do when searching for a "leaker" is to check if there are any detected unauthorized accessing of the leaked information then they compile a list of everyone who had legitimate access to the information leaked.
Most often a leaker will use someone else's access codes
so they look for people accessing the data at times they were occupied elsewhere.
Personally if I were burning a DVD I was afraid of being traced back to me I would obviously not use my own computer.
I might actually be tempted to build one out of loose "flotsam & jetsam"
around the work bench, install a temporary "Trial version" of the OS and burning software, burn the disc then dismantle the specific computer and scatter the pieces to the four winds...(drop the pieces in widely scattered dumpsters)
Oh and buy the blank discs at Walmart and pay cash...
Good luck tracing it back anywhere...