Historical Ammunition Thought Exercise (help an author out!)

I’ve been poking around for information but what I’m really looking for are some opinions. Feel free to relocate this question if appropriate. My story is that I’m a film historian, and between books I’ve been writing a detective novel; a side project to keep my creative juices flowing when the history of motion pictures gets boring. I’ve been at the novel for years, and I might even finish it in the next few decades. But every so often I manage to solidify details and bring the thing closer to completion.

I know enough about guns and ammunition to know what I have in mind for two plot points is possible. Not sure if it is likely, and certainly don’t know enough about guns and ammunition during the period I’m writing about. I also know I don’t know enough to see the glaring problems with the scenario that others would see in an instant. It’s a known unknown, to paraphrase poet Donald Rumsfeld. So, I present this as a thought exercise and invite your observations.

The story is set in 1926, and there are three weapons that are important: An M1921 Thompson submachine gun with a stick magazine (I remember enough to know the barrel magazines weren’t around yet), an M1911 pistol, and an M1917 revolver. My understanding is that all three could use the .45 acp round (if they were bored for that caliber). The owners of the three guns work for the same non-military organization and draw their ammunition from the same source (all bought in bulk by a guy always looking for a deal, maybe WWI surplus). One person is killed at short range by a shot to the head with the M1911 pistol, and then the car that the body is in is raked by the Thompson submachine gun to cover the single shot. The car is rolled off the end of a wharf in San Francisco and into the muck of the bay, the submachine gun thrown in after it, so the submachine gun is out of the picture. All the evidence spends a night in muck. When the body and car are recovered, the shot to the head is one of several wounds found on the body. At a later point the same M1911 pistol is used to shoot someone; the person who is shot manages to shoot back once with his M1917 revolver. Both die. A third person in the room (wanting it to look like they were both shot by a completely different party with the pistol) replaces the spent shell from the revolver with one from the magazine of the pistol. The revolver is replaced in the holster, the two spent shells (one from the pistol, one from the revolver) are moved so it looks like they were both discharged from the pistol at a different part of the room. The person doing the doctoring leaves the scene with the pistol. Hopefully, this is not too confusing.

In theory, it’s all possible. But what are the problems with this scenario from the ammunition point of view? Police investigating would walk into the scene already believing the two men were shot by a missing third person with the missing pistol. They would not be looking too carefully at the details. All the bullets come from the same source, so headstamps would all indicate the same manufacturer. But would markings on the two discharged shells be so glaring obvious that even the most oblivious person would see they were from different weapons? There are questions I have about powder burn and smells that I’ll take elsewhere. I’m wondering about the bullets used and shells left behind. Is there a specific manufacturer’s round that a knowledgeable person in the mid-1920s would know to buy that could reasonably be used by all three? One that would be plentiful enough to be bought in bulk? If this is entirely unrealistic, feel free to blow holes in the idea, so I can come up with something more likely. Hope the exercise is interesting and not an annoyance to the board. Thanks!

Vic, welcome here!

Today such an arrangement sure would be discovered very soon.
Back in 1926 I almost doubt that it would have been uncovered as by then forensics were way less developed and I am not sure if by then case and proj. marks were subject to investigations. That needs to be clarified.

As for the 3 guns there would be these points to be observed:

  • Rifling on the projectiles could be different and sowith identifyable
  • Spent cases would all have their specific gun marks from extractroes, ejectors, magazines and firing pins

The ammunition source I see as the least problem here if all 3 used the same since suppliers back then were not so many and could be Remington, Winchester or military surplus if being sold by 1926.

There is many more factors and points to observed and other people may have other views of course.
Just my 5 cent.

Not sure if this add anything to the story, but the Model 1917 revolver, when firing the .45 ACP, has to be used with half-moon clips and required specially crimped cartridges, although it could and was used with regular cartridges meant for pistols and submachine guns.

Alex, back in 1926 the comparison microscope was already in use by ballistics forensics pioneers like Calvin h. Goddard, who was involved in various notorious murders of that decade.



Fede, thanks!
That would limit it all then if this procedure was standard by then.

The M1911 leaves a pronounced and distinct primer indentation, easily discernable as “different” by even the untrained eye.

Can’t speak for all of the Thompsons, but mine has a firing pin that is very large in relation to the primer and pretty much crushes the whole observable surface of the stuck primer, shoving it into the primer pocket, again easibly discernable from any other firing pin strike, certainly different than what the M1911 does, which is, itself distinct.

Both firearms struck primers would be easily noted as different from the revolver’s struck primer.

But like others mentioned, modern forensics would find numerous telltales under close examination by a trained eye. My examples don’t require either. Any novice looking at the strucke primers would think, “This is odd.”

50m2hb, any chance you could show us such a primer which went through a Thompson?

EOD brings up the surplus issue and my IMPRESSION is that not a lot of that was being sold from the US government to the public at that time, however after the 2nd Great war it was much more common. Again just an impression, but at only less than 10 years after the war, ammunition produced by the US government would / should still be considered in usable condition, unless it suffered storage damage.

There were two M1917 revolvers; Colt and Smith & Wesson. Bullets fired from the Colt will show left hand twist of the rifling, Smith & Wesson right hand twist. The cases fired from a pistol will show an ejector mark on the base, which those fired from a revolver lack.
I do not quite understand the two fired cases at the crime scene. A revolver does not eject a fired case. It remains in the cylinder until the user swings the cylinder out, hits the ejector rod and then all 6 fired cases/unfired cartridges are ejected together. Due to the half-moon clips mentioned earlier, 3 cartridges are clipped together for loading and unloading in the revolver. The clips are necessary for functioning of the rimless .45 ACP cases in an ordinary revolver.

So far, so good, thanks for the observations! It looks like no problems that can’t be overcome with a little thought. I was under the impression the regular cartridges could be used with the half-moon clips, though as I said, I don’t know the subject well enough to be certain. Does anyone know how the regular .45 ACP cartridge was used with the revolver? Did it require any special equipment or modifications?
The person in the second plot point being set up to look like the shooter would have been considered smart enough to take his spent cartridges with him so as not to leave evidence behind, but then other obvious evidence is left behind. So I’ll have to work on that point. Keep it coming… the more to work with, the better. Thanks!

I should have gone into a little more detail there: the person doing the doctoring removes the half-moon clip and the spent cartridge from the cylinder, removes the spent cartridge and replaces it with an unspent round from the pistol. Then he returns the clip to the cylinder and re-holsters the gun. The two cartridges were intended to look like they were ejected from the pistol, but it’s clear to me now they would look different enough to be obvious to anyone with an experienced eye. That’s a point I’ll have to work out.

To make regular .45 ACP rounds usable in the M1917 revolver is the very purpose of the half moon clip.
The user takes 3 regular cartridges and inserts them into the clip. Loading and unloading then is done handling these little packets of 3 rounds.

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One glaring statement…throwing a 1921 Thompson into the drink…too valuable already in 1926…not money wise (no NFA yet) but desireability…
Also, the Brownsville Riots (1917) already was investigated using Goddard’s case comparison techniques.
Otherwise, scenarios as commented on above all valid.
( but a bit convoluted)

Doc AV
( semi-retd.Firearms Examiner)

Vic, it may be helpfull if you’ll try to find the user manuals and/or technical manuals for the guns in question.
Having that as a supporting basis to work from may help.

Here some bits on the revolvers:

The half-moon clips were not required in order to fire .45 ACP cartridges in the Smith & Wesson and later production Colt 1917 revolvers. However, the clips were necessary in order to eject the spent cases without having to resort to working the cases out of the chambers individually. Early Colt production 1917 revolvers, on the other hand, had bored through chambers that required the clips to maintain the correct headspace for firing.

A few minor points: First, both 1917’s used half-moon clips (meaning three rounds per clip, and they truly are “clips”, not magazines). I’ve never used the clips but I’ve read that it is difficult to put rounds into them and as hard, if not harder, to take them out. If this is correct, it is quite possible to be too difficult to get the empty case out of the clip while “…in the field.”

Second, ammo shot from a semiautomatic gun has markings on the case that are not on the cases from revolvers. They could include scratches put on the side of the case from being inserted into the Colt’s magazine (not a “clip”, as I’m sure you already know), two longitudinal marks of about the same length and about 180 degrees from each other, extractor marks on one side of the case, inside the groove at the head of the case and ejector marks on the actual base of the case, in one spot only. Those are the MINIMUM markings that might be found. And they can all be found with a magnifying glass. Other marks that could be found are ones where cases hit the gun. Many 1911’s that haven’t been “ported” could have a specific place where the mouth of the case gets a dent from every round fired in it. If, for example, two cases have dents in the sides of the mouth that are the same depth of dent (say, for example, that both dents go in 1/8" and both dents were 1/4" long and were the only cases at the scene), then they would most likely have come from the same gun. A revolver cartridge would receive none of these marks.

Another suggestion is that, if the murders are premeditated, there is no reason that the crook could not have gone out to a rural field, fired a few rounds, then picked up some spent cases to “plant” at the crime scene.

Now, if the police want to see if two cases were fired from the same gun, then there are two techniques that could be used back then. One was the aforementioned comparison microscope. Another was to take really good close-up photos of the two cases and cut an edge on each photo and put them side by side. Only the best labs had comparison microscopes back then as they we expensive and the majority of police departments didn’t have enough murders to justify the cost, or could not possibly have a budget that would pay for that.

Also, .45 slugs usually don’t have enough velocity to punch all the way through something like a car or a couple of walls. Their energy comes from a very heavy bullet moving at modest speed - inertia. Some .45 slugs would just put very large dents in the “lead sleds” of the time, especially if they hit the car at an angle. This would make it easy to locate at least some of the slugs. Those that did make it through one door is unlikely to have enough power left to go through the sheet metal on the other side.

More notes to help you:

The magazines for Thompsons are called “drum magazines”, not “barrel magazines”. Easy to mistake.

Note that the angle of the head entry could very easily be different from the angle from the Thompson.

If the police found the car off the end of the wharf, they WOULD find that Thompson. All they would have to do is draw a large magnet behind a boat. It would likely have to be thrown at least a few hundred yards from where the car went in and then they still might find it.

Firing pins always leave a mark on the primer. I do not know what the firing pins from these three guns look like, but they would all have to be similar (depth of indent, diameter of the firing pin, loose space around the firing pin, etc.

If they really want to solve this case (as opposed to “Let the crooks kill each other. Doesn’t bother me.”) then they WILL look very closely with any current technology possible.

It was correctly said before that Colts use a left-hand rifling twist and most everyone else used (and still do) right-hand twists. Therefore, to confuse the police, both have to have the same twist handedness.

This has been a fun exercise. If I can be of any more help, let me know.

Also, last year I bought a book on firearms forensic procedures from about the same era as your novel is set in. I’ll see if I can locate it among the several hundred other gun and ammunition-related books that I have. If I can, I’ll be glad to look through it to see if anything in it might be helpful to you.

Any and all of these details could be either confirmed or unconfirmed by altering a detail or two.

Best of luck.

R. Theron Cammer

R. Theron Cammer: This is some good information; looking back at what I had written in the novel regarding the shooting in the car, I had a character mention that there were no bullet holes or dents in the body of the car itself, so it was assumed the submachine gun was fired through the passenger side window from close range. Thus, the fatal first shot had a similar angle to the rest of the bullets. At least close enough like not to arouse suspicions. But at a later point I wrote something that contradicted that… it’s something I’ll have to straighten out. The idea of firing two sacrificial rounds from the pistol to leave behind at the scene later is good. That goes into the finished product.
As to the attitude of the police, they’ll be generally motivated to go with the least complicated explanation. So they’ll dig only as far as they have to. If you find the title of the forensics book, let me know the title, year and publisher. I work at a library at Stanford, and can request just about any book I need.

How about taking the empty case from the revolver, load it in the 1911 and chamber it, fire and eject manually to at least get some correct markings from the pistol on the empty case?

Firearms Identification by Calvin Goddard. Compiled by Neal E. Trckel
Privately published by Neal. it is a typewritten copy of the book, of pioneer Goddard’s until now unpublished notes on Forensic’s

I’ll send you a PM with his phone number / details

Others who might be interested PM me cost is $35.00 I think & it’s very interesting

Handbook of Firearms and Ballistics: Examining and

Interpreting Forensic Evidence (Developments in

Forensic Science by Heard, Brian J. (Amazon)

I kind of assumed that your intention was to put them through the windows. Just be aware of two things: If he’s already been shot in the head, his head will hang down and not be reached by any of the bullets that go through the car unless they go through the doors. Blood spatter would also likely not match the angle of the head shot, either.

Also, what I meant about the angles of the shots, if even one shot goes through anything other than air and has an entry and an exit (or dent(s)), that trajectory will be different from the angle through the head. The only way they could be the same angle is if the head was upright and shot from head height or a bit below. Another aspect of this if the crooks’ intention was to make it look like the car was shot while moving (necessary if it’s going to go off the pier without someone pushing it), then EVERY SHOT has a different angle of entry and exit since the muzzle of the gun would constantly be changing angles with the car as it drives along.

I got a degree in Criminal Justice in 1977. Several of our instructors were police officers. Our Criminalistics class was a retired New York State Trooper who brought in actual crime scene photos. While the cops in your book quite possibly could have an “Ah, so what?” attitude (certainly don’t change it on my account, as bad cops make for good novels), in the era of your novel most local police departments would have likely sent them to the state crime lab. I can tell you, the New York State Crime Lab doesn’t miss ANYTHING!

Glad that I could be of help. The name of the book is above. If you can’t find it, let me know.

I don’t try to pick things apart, but I do read a lot of novels and see things that could have been written tighter. It looks like at least you’re doing good research into things.

I have owned and fired several M1917 revolvers in .45 ACP - they do not require “specially crimped cartridges” - any .standard 45 ACP round fits and fires fine. As others have already mentioned, half or full-moon clips to hold the cartridges for extraction may or may not be required, depending on the model. Perhaps I misunderstand what you mean by “specially crimped cartridges”?