polygon barrel and fired bullet ID

[prairiedog555]

Hello,
I just bought a CZ 82 with a polygon barrel and I was wondering if law enforcement can identify a fired bullet since it has no rifling.
I figured you gunsmith guys would be the best to ask.
Thanks

[alsaqr]

 

I was wondering if law enforcement can identify a fired bullet since it has no rifling.

My ballistics guru friend says that they can.   

[S.S.]

there are still machining marks and irregularities in the forging that
will allow ballistic ID.

[Kmrere42]

Hi,

Just had to add something here.  Anytime there is bullet to barrel contact there will be marks left on the bullet. There are really only two situations where no real marks will be left on the bullet.  One is with Remington style accelerator sabots where the marks will be on the sabot and the second is with paper patching,  the marks will be left on the paper patch which will be shredded. If the patch is thick enough there will be little if any deformation of the bullet.  Paper patching is really an art.  I have tried it and have mediocre results. Even jacketed bullets can be patched but it takes a bit of prep work.

Hope this helps.


Paul

[trotterlg]

I would think, there could be two or (many) more hammer forged barrels that had very simular marks depending on where the barrels were cut from the blank.  If the barrels used the same mandrell for forming they will have the same machine marks in them.  Pistol barrels are most likely cut from a longer barrel, so depending on the section of barrel that is cut, there may be dozens of barrels out there that have very simular internal machine marks.  Probably not exactly the same but very close.  How many simular marks in a barrel would be enough to send you up the river for a long time?  Larry

[Kmrere42]

Hi trotterlg,


Actually the chamber cut/forcing cone, will create the most marks as the bullet is swagged down to the bore.  The bullet then gets marked by any high spots as it travels down the bore. If the bullet is slightly undersized for the grove diameter and was centered properly, there might be only burn marks except where the lands engraved themselves.

Just firelap the barrel after your trip to the dark side to hide this type of evidence. Not that its good to do EVIL, Please don't...


Paul

[trotterlg]

Hadn't really thought about the forcing cone issue, that and any brass would probably make the ID.  The paper patching is a thought, kind of like a very thin Sabot.  So, I guess, a polygonal rifled revolver loaded with paper patched bullets would be the trick.  Larry

[conradj]

yes, forensics use rifling to identify bullets but all barrels of the same brand of production barrels are identical , so forensics also use microscopes to match projectiles to the microscopic marks in a barrel cased by either wear and tear or manufacturing inconsistancies caused by warn tooling when produced etc.

so in short forensic scientists do use rifling to identify a certain gun brand and then use microscopic indifferances to individualize a single barrel.

Hello,
I just bought a CZ 82 with a polygon barrel and I was wondering if law enforcement can identify a fired bullet since it has no rifling.
I figured you gunsmith guys would be the best to ask.
Thanks

[SHOOTALL]

The empty case is a biggie also as ofter a bullet can be deformed depending on what it hits . Both - got ya !

[davestewart38]

Glock barrels have polygonal rifling.In police shootings with multiple guns individual guns could not be identified.Glock makes special barrels with grooves for police departments so that individual barrels can be identified.Bullets fired in the barrels sold to the public cannot be readily matched to the guns that fired them.There are still  characteristic markings left on fired cartridge cases such as the firing pin indentation in the primer and marks left by the extractor and ejector which may allow identification of a particular gun.So pick up your brass http://policechiefmagazine.org/magazine/index.cfm?fuseaction=display_arch&article_id=1893&issue_id=92009

[coyotejoe]

Forensic ballistics is highly over rated and in my opinion should not be allowed as evidence in court since declaring a match comes down to the opinion of the technician, just like in lie detector evidence. There is no such thing as a "perfect match". While no two guns will mark their bullets identically, neither will any one gun mark two bullets identically. There are many random and unrepeatable factors such as dust, grit and powder and bullet residue in the bore, all of which will mark a bullet. The bullet itself will have marks from manufacture, handling and loading into a case even before it is fired. High quality barrels are made as nearly identical as can be so the differences are minute. When examining in such minute detail, those random markings are very prominent. For every mark which matches there will be a dozen which don't match.
 So it always comes down to an opinion and that is never an unbiased opinion. The fact that the technician is given a gun to test tells him it is expected to match. One case which comes to mind was when Claude Dallas shot two game wardens in Idaho. The state "expert" declared a Ruger .357 magnum revolver as a positive match to the lethal bullet. What the state's expert didn't know was that revolver didn't belong to Dallas but to the principal witness against Dallas. The state's "expert" then reexamined the bullet and said it "probably" did not match.   There have been many cases where the prosecution's expert declared a match and the defence hired an expert who disputed the match. There would no doubt be more such instances were it not for the fact that most defendants cannot afford to hire their own expert.
I have a real problem with TV shows like "CSI" because jurors will believe that crap is factual and "scientific evidence" is beyond dispute. It is useful in guiding an investigation in the right direction but in and of itself should not be considered as "proof" of anything.