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Justin,

You may want to read some DGJ articles by Ross Seyfried and Sherman Bell. The articles are great on loading NfB loads. Also, Graeme Wright's book Shooting the British Double Rifle discusses chamber ringing and includes a picture.

Ken

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Since most of us are unlikely to run across a copy of Wright's book, do you suppose you could give us a quick rundown of what he wrote about chamber ringing? Please?

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KDGJ
I can’t recall Seyfried or Bell discussing chamber ring bulges. If you have a specific article in mind,please let me know.

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DGJ 2011 summer Bell has a great article on fillers.

https://www.castbulletengineering.com.au/downloads?download=9:finding-out-for-myself-express-rifle-case-fillers-by-sherman-bell-thanks-to-the-dgj


http://www.bertramandco.com/

ACGG Professional metalsmith, firearms import services.
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Justin,

Seyfried briefly touches on chamber ringing in Vol 10, Issue 4. His articles in Vol 5, Issue 4 and Vol 6, Issue 1 provide his techniques/approach for loading NfB loads. As Steve mentioned, Bell did an extensive set of articles on Finding Out for Myself with specifics on NfB loads. These can be found in Vol 15, Issue 1; Vol 15, Issue 4; Vol 16, Issue 1; Vol 19, Issue 3; and Vol 22; Issue 2 (Express Rifle Case Fillers). The issue looks at pressure spikes with the different fillers.

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Sherman Bell's testing was very interesting and covered the gamut of filler material. He said he was surprised that the closed cell foam which he knew of to have caused 2 instances of chamber ringing did not show any reason in his test to have done so. What he did not test was any powder except 4198. He did not mention if the two instances of ringing involved 4198 or some other powder or if those instances were in older barrels which he admitted may be at more risk than the modern barrel material he was using. I would be mindful of the tests that produced "stepping" of the pressure curves as the more likely problem makers under slightly different conditions.

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Originally Posted By: HalfaDouble
Since most of us are unlikely to run across a copy of Wright's book, do you suppose you could give us a quick rundown of what he wrote about chamber ringing? Please?


He believes it is a result of airspace within the load. The airspace allows for a pressure wave to be created. The theory is based on Paul Vieille's (1890) theory of "Wave" pressure. Burrard in The Modern Shotgun (1948) summarized Vieille's theory to explain what happens inside a cartridge case. Vieille proved that the high end pressures were caused by the movement of the hot and very elastic powder gases When the powder is ignited at one end, a wave of high speed gases accelerated through the airspace. As the wave hit the solid end it stopped, and as the following gases piled up behind, the forward layers were compressed violently causing a localized area of high pressure.

(You already mentioned this book by Dell and it is in Wright's write-up on Chamber Ringing): Charles Dell co-wrote The Modern Schuetzen Rifle (2nd Edition 1999) with Wayne Schwartz. Charles Dell was able to backup Vieille"s theory. That is, chamber ringing is caused by high velocity gases hitting the base of a stationary bullet. This creates a very thin, but high pressure gas area at the bullet base, and when this exeeds the yield strength of the chamber steel, a ringe is formed.

Ken

Last edited by KDGJ; 08/14/20 12:45 AM.
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Thank you SKB and KDGJ. I will get on these articles ASAP.

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Anybody really interested in this discussion should actually read the Bell article( SKB above showed a link to the article) in detail, especially the conclusions and the pressure curves/chart. His testing of 15 ,different materials/methods failed to show any significant spike in pressure. Regarding the "stepping" or "stuttering", a study of the pressure curve shows that the pressure actually dropped( likely when the bullet started moving, chamber volume increased, slightly lowering pressure until it "caught up"), but never showed enough pressure to ring a chamber. In his conclusion he stated " The obvious elephant in the room is that no excess pressure developed from the use of these widely different filler material". One of the most "telling" results was the showing that the system currently used by Kynoch produces some of the highest pressures, and they are still not excessive. I will continue to use a "tuft" of kapok tamped down on the powder, as I have for half a century; but I will be responsible, myself, if anything happens. I have never seen a "ringed" chamber but enough other people talk about them that there must be some basis. Maybe someone that has a rifle with such a chamber will closely examine it for significant prior use with shorter cases. This may create a "ring" by erosion and if a new owner starts loading proper length cases( much easier to find now than years ago), it may take a few reloadings of new thicker cases to expand into "old" chamber rings, causing extraction problems. This is just a thought, not a proven fact.
Mike

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Mike, Charlie Dell started with a fresh cut chamber and the ring formed at the position of the base of the bullet.

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