Here’s a sectioned cartridge, identified only as 25 mm French. The headstamp is HOTCHKISS (12 o’clock) 34 (3 o’clock) PARIS (6 o’clock). Whatever was at the 9 o’clock position in the headstamp was removed when it was sectioned. The case is 194mm long. Tony lists a 25 x 194R Hotchkiss in his 'Rapid Fire, but nothing on a rimless. Any info would be appreciated.
It is an experimental round and those around in Europe were found at the air force prooving ground at Rechlin in north east Germany.
The projectile should be seated deeper inside the case, means the second driving band should rest on the case mouth.
Thanks, EOD. That projectile has been pinned in place, I assume by whoever sectioned the cartridge.
That is really nice. I just noticed that each grain of powder has a small hole running threw the middle. I wonder how they do that? Anyhow, the sectioning is done very nicely. A beauty for sure!
Those ‘powder’ grains are something other than powder; I think perhaps short lengths of electrical wire insulation. One of the grains broke off, and I tried what could have been one of those stupid collector tricks and tested it with a Bic lighter - it melted and eventually began burning. I’d have really been shocked and probably would have jumped out of my skin if it had flared up.
WOW! Lucky 4 sure! That is a good idea to use the wire insulation to simulate the powder. I have seen photographs of large tank shells sectioned with really massive grains of powder and they actually had a bunch of tiny holes or perforations in them. I would love it if the Discovery Channel did a documentary on the manufacturing of all kinds of ammunition and its components. As seen by some of these amazing sectioned rounds, their is some extreme design and manufacturing brilliance involved.
The real powder in this cartridge may have been perforated, many powder granules are. The hole, or holes, are there to regulate the rate of burning. If a powder is solid, without any perforations, then the area exposed to burning reduces as the grain is consumed. If there is a hole through the centre of the grain then the outer layers burn away, reducing the area, whilst the inside of the hole gets larger, exposing more area as it burns. In this way the surface area can remain nearly constant. Sticks of cordite frequently have one or more holes through the length for the same reason. Larger powder granules for artillery may have several holes.
Putting a flame to one or two powder grains will result in a small flare, but nothing frightening. You can safely hold one end of a stick of cordite and light the other end. There is time to admire the pretty flame and let go before it reaches your fingers. Don’t try this with a bunch of sticks 'though, both pressure and temperature accelerate the rate of burning, see my stupid trick described in the forum a few days ago.
Powder for large calibers are usually perforated with anywhere from one to seven or more holes. This is done for two reasons.
In the larger grains, which are nearly 1 inch in diameter, the holes provide a larger burning surface area. The holes also makes the powder progressive burning which means that as grain burns the total surface area increases since it is burning both from the inside and the outside.
A grain with a single hole is neutral burning since the inner surface increases at the same rate that the outer surface decreases.
A grain with no perforation is degressive burning since the burning area decreases as it burns.
All of this is black magic concocted by ballisticians to control the rate and time of burning and therefore the pressure rise and fall appropriate to the particular weapon.
PS - It looks like gravelbelly was posting whilst I was typing. Oh well, at least we said the same thing.
The grains BTW are made in the same manner as making pasta. The doughy mixture is extruded through a die while a rotating blade cuts off the spaghetti at the correct lengths.
Thanks Ron & Gravelbelly for the great, detailed explanation of how powder is manufactured and its functional design. Really fascinating stuff. I would love to watch the large grains being manufactured. Now, the perforations make allot of sense. As always, thank you experienced experts for sharing your wealth of knowledge.