.450 Rev. blank for Michelin tire pressure alarm?


Pete DeCoux, during a recent visit here in the land of taxes and gun laws and I spent several hours picking through the back room, front room and office of a gun shop that I work in 1 day a week (to support my clay target shooting habit). To be clear, Pete did most of the picking. I was getting educated, so was the owner. One of many curiosities discovered was about 10 small blank cartridges, hdstp,
.450 Rem-UMC
crimped/star type crimp (I don’t have one in front of me but I think it was an 8 fold crimp) that appears to be soldered/sealed. Peter acquired 2 of them and it appears that they may be for an invention by Michelin to let your chauffeur know that the tire pressure has dropped. Pete had consulted with someone that suggested the Michelin connection. I unfortunately did not take any photo’s of the cartridge but will this week.
The patent description does not specify what the cartridge is but the schematic drawing shows a cartridge in place in the device, strongly resembling this cartridge. A second similar patent was granted to Michelin 2 years later and in 1947 another patent was granted to an American with a similar device that used a .22 rimfire blank. Can anyone verify the .450 Rem blank/industrial round? And how do you go about soldering/sealing the crimp without risking setting off the round? Even a very low melting point solder would require heating the case to some degree to get a good bond?



Chris Punnett (IAA Journal editor) in his recent book The .450 Short Revolver Cartridge covers this cartridge in some detail and he indicates it was produced by SFM, Leon Beaux & Co., Milan and one possibly made by Rem-UMC.


Edit: Chris indicates that the blanks produced by SFM have a thick wad over the powder charge which may explain the ability to seal the crimped case mouth with solder.


I do not know why a blank for the Michelin flat tire warning system would exist with a REM-UMC headstamp, but it does. SFM, and its associated companies like LBC, made the majority of them. They had plenty of cases so I don’t see that they would have asked Remington to supply cases, neither do I see why Michelin would need to give Remington a contract to produce the blanks. I’m not saying they didn’t - just that I can’t explain it. A. J. Michelin did hold a US Patent (1,367,490) for the device so maybe they thought they’d try a US manufacturer in case they got an order from a US municipality for the device for their street cars/trams???

Anyway, I hope to section one of the REM-UMC ones in the foreseeable future to see if they are identical internally.

And you all thought the .450 was boring !!!


Thank you all for the interesting info! I will have to get a copy of the book. What was the propellant / charge In the cases you have sectioned? Interesting.


I can’t add anything regarding the relationship between Remington and Michelin, but the soldered star crimp used in these cartridges was patented by SFM in 1923 (application filled in 1922). It was designed as a method to ensure the watertightness of the closure and to enable the use of a weaker charge, producing the same noise level as an unsoldered cartridge with a heavier charge, however.


Thanks Fede,

I assume you are referring to French patent 556,012 for the soldered crimp? I do not know if there was an equivalent US patent?

The powder charge in the common French-made Michelin Device blank is 0.4 grams (6.2 grains) of BP according to SFM drawing #10027C, dated August 1922. Those that I have taken apart had a compressed charge and I was unable to confirm the exact weight.

I should quickly point out, in case I’m misquoted, that there are [at least?] three basic types of French puncture warning device blanks, two of them with solder-seal crimp:

(1) The common “Michelin Device” which has the short case, 6.2 grains of BP and thick wad. SFM drawing 10027C dated Aug 8 1922.

(2) The later, slightly longer case, usually headstamped GG 450M, SFM Drawing 10026E dated Dec 4 1926, using a charge of 0.3 grams (4.6 grains) of smokeless powder plus a layer of o.35 grams (5.4 grains) of Potassium Chloride as a flame retardant with a thick wad under the crimp. Photo attached.

(3) The short case with the raised band ½ way up the case which is a special model for England (no mention of Michelin on the SFM drawing, 10027F dated March 17 1928), The drawing does however state that it is “without flame” implying that it has the Potassium Chloride flame retardant but I have not confirmed that personally. Neither do I have information about the propellant charge. This blank also occurs in .38.

Edit: banded case blank does NOT have a solder-sealed crimp


A “450M” or .450 Michelin. I can’t believe I am actually reading this thread! I think I am going to go wash my brain out with a good detergent, probably a 2005 Claret.

What is a respectable 9mm Para collector doing on this thread?




A friend of mine who is a railroad fan and vintage auto collector thought that these trolley / urban commuter trains from the 20’s and 30’s with pneumatic wheels might have been the reason for development. He thinks he remembers reading about the cartridge alarm on trolley wheels…?
If he finds the source I will post. The link above has a photo of the type of trolley.