Quadratic and conical flash channels - UK Bayliss patent in Germany

I came across documents describing quadratic and conical flash channels.
My first encounter was in French and German documents on 37x94R Hotchkiss cases and initially I thought this design has originated in France as Germany was a licence holder for the ammo.
But later I also found such flash channels being described for (DWM made?) 9.5mm Turkish Mauser cases dated 1887.


  • What was the exact purpose of this shape (I suspect a venturi effect which created a faster/hotter flame jet)
  • Who invented it? Was this ever patented?

Here a drawing from a German 1886 document.

I am convinced, that this was only for practical reasons in the manufacture of the die. With tools, is easier to make a very small pyramid than a cone.

I do not think so as for me as a mechanic the opposite is the case. Let us see what people will come up with.

THV echo’s my 1st thought as to the why of this. Other than that I do not know.

At that time there was no laser, CNC … many small things were done by hand in one piece. I doubt that the square hole had a different or better effect for igniting black powder.

Conical holes assumingly would have created a jet effect, making the jet faster and hotter.
As for why and how I am very interested to hear.
And the 37x94R Hotchkiss was later loaded with nitrocellulose power if I got it right.
Having a better ignition may have saved the primary charge in the case then or would have improved ignition at low temperatures.
Just my thoughts and this is the reason why I would like to see some primary source info if that is available.

Alex, I don’t know the exact reason for this shape nor of any patent from that era dealing with these flash holes. You can also find them in contemporary Berdan battery cup primers for large caliber cases. Below you can seen an example of a primer for a Hotchkiss patent 37 mm case:


Generally speaking, German solid drawn Berdan cartridge cases using this construction were based on the British Bayliss 1874 patent (BSA&MCo), but the shape of the tool for punching the flash holes has this shape:



Fede, yes, am familiar with the Hotchkiss drawing of that primer.

The Bayliss tool here looks very interesting as it may be what I am after.
I will try to find the patent.
Thanks for the lead!

US159883A.pdf (643.4 KB)

Fede, this is great, thanks a lot !!!

As I wrote, it is only from the practical point of view in the simpler production of tools. No science …
Try to make two cones on such a small tool!

Now I got confirmation that Germany was using the Bayliss patent on small arms cases like the 11x50R Mauser. And from the drawings we know they did with 37x94R too.

I just need to find if Hotchkiss (first in the US and then in France) also used this patent (most likely).