Brake test cartridges

Started on the Thompson SMG Riot thread

The following input took place.
From me:
Here are two Peters boxes with similar contents but different uses. The top box has the contents of the video and the cartridge on the left The bottom box (which does not mention the Thompson) has the middle and right examples (also is shown disassembled). Notice the lack of case crimps on the brake test example, which are also much lighter in weight.

Then John Moss contributed this. (I’ve taken the liberty to copy his thread here)



Pete - thanks for posting that box label. The Brake Reflex Test cartridges are far rarer than the shot rounds. While there are many variations of the Peters shot cartridges, I have only ever found two variations of what are reported to be the Brake Reflex Test rounds. Both rounds are headstamped “PETERS .45 A.C.” but differ in most other details:

Earliest of the 2 BRT rounds: Red Paper Sabot, brass case with no cannelures, nickel domed primer cup with red primer seal. OACW: 151.7 grains (9.82 Grams).

Later version of the 2 BRT rounds: Red Paper Sabot, brass case with two cannelures, upper one smooth and lower one knurled, nickel flat primer cup with no primer seal. OACW 121.9 grains (7.86 grams).

I cannot explain the 30 grain difference in weight between the one with no cannelures and the one with two cannelures. I am loathe to pull them apart, as I had no duplicates of either. For comparison, a shot cartridge of the same description as first round as to primer, primer seal etc., but with the two cannelures, has an overall cartridge weight of 285.6 grains (18.5 grams).

It is interesting that the over-labeled box for the BRT rounds seems to have no mention of their purpose. I was not aware that the BRT rounds were ever used in a conventional firearm. My understanding was that they were for a special fixture, mounted to the undercarriage of an actual automobile, and that when the break was applied in view of a visible warning, it actually fired the yellow-chalk projectile into the ground, living a visible mark that showed the exact distance between sighting of the hazard warning and application of the brake.

I have never seen anything on this fixture, so am not at all sure that description is accurate. When I took a driving test in the Army (actually in the Army Reserve, after my active duty tour), all this was down on a testing machine that was basically a video game. It was all done electronically, even though that was some 58 to 60 years ago.

I failed to mention in my original entry that the commercially headstamp versions of the shot cartridges are much more common than are those headstamp “R A” but perhaps a little scarcer than the Evansville Chrysler military versions.

John Moss

Then I answered with this

Interesting John.

I’m going to start another thread on Brake test’s as I have another box.

The total weight of the one I showed is 147.8 grains (so pretty close) & otherwise meets the description of your earliest.

I also have one that is of the same description of your 'later" example, however it weighs only 251.4 grains & I can hear the shot when I shake it (so perhaps it’s lost a couple shot?), so it’s obviously not a brake test.

I’ve also heard the story of a fixture but with the addition of a lanyard to fire it.

But to my mind to record the distance between the sighting and the brake being applied and the actual stopping point would need two markers. So I believe / think these were only for stopping distance tests as it could easily function to mark when the brakes were first applied / the gun fired to where the vehicle came to a full stop.

So from here on is new, continued from that thread, but only about brake test cartridges.

Here is another box. .38 S&W Special, Remington Target Master turned inside out and containing REM-UMC, PETERS and WESTERN headstamped brass, nickel primers and white topwads

So last night I got an e-mail from a friend with more information about the testing and the rimfire rounds!


Pete - I should have put my latest reply on this thread, but I hadn’t looked at it yet and seen that you reported the “findings” from the previous thread. Perhaps you or someone else who knows something about computers can transfer that one to this thread. If I get to doing cartridge weights of all the variations I have, I will post it here.


Done John (just copy & paste)


Pete - I did not word my explanation of the device very well. It confuses even me. I think you are right about the two contacts, and tried to explain that. There likely was a portable sign that the instructors could put out saying something like “Hazard” or “brake” and that the distance from that sign or whatever visual warning was used, to the yellow chalk on the pavement, measured the reflex distance between warning and using the brake.

That is all conjecture on my part, because I have never seen the device or know if it really was used. The chalk tells me that it is logical that it did. Firing a chalk-laden projectile from a pistol would seem to serve no purpose at all.

The elctronic device used in my military driving test essentially worked the same way, but all electronically. The hazard warning came on the screen, in cartoon form but I don’t remember what it was, and you had to hit the brake, which was an actual floor pedal like in a real car, and then the distance between warning and initial use of the brake was measured electronically. No cartridge of any kind was needed.

I think if I have time today, I will weigh all of my T23 style (which was later changed to “M12”) cartridges by Remington/Peters. I weighed only the two that I believe to be Brake Reflex Test rounds, against a known shot round of the same headstamp and primer as the former.

Pete - Thank you. You guys are wizards with these infernal machines. I see “copy & paste” all the time, but have no idea how to do it. Don’t need an explanation, because it is a feature I like will never use.

I will try to get to weighing these rounds today, and will post the results on this thread.

John M.

I saw this brake test device in use when I took driver ed in high school. this would have been 1964. They demonstrated it in the main driveway I saw it used again by the NYS police at their driver training grounds at the Schenectady County Airport (Sch’dy, NY) about 15 years ago. The NSP academy uses the old General Electric test flight center runways that are part of the county airport and 109th ANG.

Evidently I cannot edit my posts that were transferred to this site, since I did not post them here. In one response above, I referred to a shot cartridge as the M23. My head was somewhere else when I typed that. The correct initial military designation was “T-23,” which was later changed to “M12”. These are the shot cartridges with the red sabots under discussion.

John Moss

Hi John
made the edit / change,

thank you. I have weighed all my Paper Sabot Remington/Peters/Evansville Chrysler military and commercial shot cartridges, but decided I will post them on the original thread about Thompson SMG shot rounds, since they are not Brake Reflex Test Rounds.

John M.

Here is a picture of a sectioned brake ctg.