Watching some TV series with forensics.  i understand the reality vs. fiction portions, but when they locate a projectile in a body and state, "Looks like a .38, but ballistics will confirm," it makes me wonder.

Isn't a .38 projectile nearly identical to a 9mm?  Would it be more accurate to state it's probably a .38 OR 9mm before ballistics identifies it?

Is there a way to see if a projectile was from a revolver vs. a semi-auto?  Without the weapon and/or casing, i wouldn't think so.  The ME didn't doing any weighing or measuring -- just made the statement upon visual discovery.

Things that make me go, 'Hmmmmm."

 

I think it was the 1st season of Reacher where he said that a 95 grain bullet was from a 9mm.  that's a 380 weight not 9mm. but you know hollywood

I would think that between a 38 and 9mm, once it hits a human target and the bullet gets deformed somewhat, it would be hard to determine what it is.  since there's only a .001" difference in diameter and similar bullet weights and bullet fragments could be lost once it hits its' target

I would think that between a 38 and 9mm, once it hits a human target and the bullet gets deformed somewhat, it would be hard to determine what it is.  since there's only a .001" difference in diameter and similar bullet weights and bullet fragments could be lost once it hits its' target

That's my understanding, too. 

Before the early 1990s, .38/.357 pistols were more common especially for law enforcement.  Sometime in the 90s, semi-auto 9mm handguns became more popular, but .38/.357 pistols were still owned/issued/used.  There would have been a transition period where 9mm ownership and use exceeded .38s.

That meant the chances were much higher a bullet would be from a .38 versus a 9mm prior to some point in time.

Things change over time.  So do the chances of an assumption being true.

I spoke to a public defender and they often use lack of DNA to try get their clients off the hook. Since the TV show CSI came out, more people know about DNA and these test are expensive to do.  The state won't do it for every case, unless it's a big one.  So the absence of DNA is a strong tool that PD's use.

So even though TV shows can get stuff wrong, it gives the public the general idea of things.

I spoke to a public defender and they often use lack of DNA to try get their clients off the hook. Since the TV show CSI came out, more people know about DNA and these test are expensive to do.  The state won't do it for every case, unless it's a big one.  So the absence of DNA is a strong tool that PD's use.

So even though TV shows can get stuff wrong, it gives the public the general idea of things.

i was more focused on bullets, not a general discussion on how TV or other entertainment has impacted the justice system.

I don't reload, so i was putting this out there in case there's a "trick" to identifying .38 and/or 9mm bullets I don't know about.

 

i was more focused on bullets, not a general discussion on how TV or other entertainment has impacted the justice system.

I don't reload, so i was putting this out there in case there's a "trick" to identifying .38 and/or 9mm bullets I don't know about.

 

The revolver that I was looking at could shoot both 9mm or 38.  Well, I think that was it. Or it was some other caliber that can fire out of the same gun like 357 and 38.  This was very long ago. Like how you could shoot a 22 LR out of a 5.56/223 AR.

I wonder if on the head, they could tell by any marking left from the feed ramp from a semi auto, compared to a revolver.

The revolver that I was looking at could shoot both 9mm or 38.  Well, I think that was it. Or it was some other caliber that can fire out of the same gun like 357 and 38.  This was very long ago. Like how you could shoot a 22 LR out of a 5.56/223 AR.

I wonder if on the head, they could tell by any marking left from the feed ramp from a semi auto, compared to a revolver.

Not an expert, but ...

I believe the chamber is larger than the casing.  When fired, the casing expands to trap the gases and propel the projectile.  if your chamber is smooth, there would be no markings from loading a round.  Same should be true of the ramp, but even more so.  The ramp is not fully enclosed, so there's less chance there would be enough pressure against the ramp to create marks.

Theoretically, I don't think you should be seeing any marks on a bullet before it's fired after it's chambered.  If you do, polishing the feed ramp and/or chamber may be needed for a smooth loading and ejection.

Easy enough to test i suppose.  Cycle the slide 10 times on a full mag and check for marks on the bullet.  Since I'm mostly interested in 9mm, other calibers would not be as objective a test.  Of course, you'd be running the round through both loading and ejecting steps, so any marks could potentially be from ejecting as opposed to loading, meaning any pre-firing marks may not be on a fired bullet.

Just thinking out loud.

I worked on a murder case like that around 30 years ago.
It all worked out eventually.

Main difference is bullet type, weight and velocity.  If the bullet is 158grains, then it's a 38. If it's a wadcutter then it's most likely a 38.  Probably other types of bullets in 38 not available in 9mm.  Might be able to calculate the velocity of the round.  Though there are 38+ps and subsonic 9mm so it could overlap.

Main difference is bullet type, weight and velocity.  If the bullet is 158grains, then it's a 38. If it's a wadcutter then it's most likely a 38.  Probably other types of bullets in 38 not available in 9mm.  Might be able to calculate the velocity of the round.  Though there are 38+ps and subsonic 9mm so it could overlap.

My question is whether or not a medical examiner or other experienced forensics person can accurately discern the
caliber based on bullet type, weight, velocity and/or any other characteristics at the moment they discover and
extract the bullet from a victim before any measurements are taken.

What you're describing would be observed by the ballistics techs IMO.

Aside from recognizing the shape of the bullet I cannot think of any way a forensic examiner would be able to tell which one is which.

125/124 grain bullet could be either one

twist rate 1:10 vs 1:18. with a little bit of training you can probably tell the difference in seconds if the jacket and witness marks are present. thats why i always use ice bullets. 

Main difference is bullet type, weight and velocity.  If the bullet is 158grains, then it's a 38...

I've loaded 160 gr .38 bullets over 2.6 grains of Tite Group to make some pretty quiet loads for my AR9, but those were only really good under 50 yards. I imagine it would make the firearms tech in SIS scratch her head trying to figure out the platform if she found the slug at a scene!