Ringing a chamber?

[tomme boy]

What is it, what causes it? I have seen it mentioned a few times and no one has really said what it is.

[geargnasher]

Tamping a wad down against powder and leaving air space between the wad and boolit base is a really good way to ring a chamber.

Gear

[emrah]

Ok, but I'm with the OP: WHAT is it?

Emrah

[PuppetZ]

A slight depression "stamped" in the chamber. It is caused by a small charge being plugged in place by a tight wad, usually a powdered filler that harden in the case and plug it tight (the various cream of **** are notorious for that. If they are exposed to moisture, they can clump and clog a bottleneck case shut). It cause a very severe overpressure situation but just on the small length of the case that contain the powder, stretching the metal of the chamber around the case in that location. Since the case is round, it bear the shape of a ring. To prevent situations where a ringing of the chamber could occur, do not use a powdered filler like cream of wheat. Never compress a fiber filler on your charge, leave it fluffed.

Hope that help.

Frank

[runfiverun]

think of it like a piston driving air forward. [except at very high velocity]
and the air has no where to go.
this forces the steel outwards in a circle where the air is contained.
at times it can lock a fired case into the chamber.

don't confuse ths with a belly bulge from a wobbly cut chamber.

[tomme boy]

Can it happen without any filler. Reason is, I had a Yugo mauser about 15 years ago that I put a ring in the chamber. I was using Blue Dot powder and 175 gr j-words. It happened with 15 gr of powder. It was not bad enough to hold a case, but you could see it in the chamber. It happened about 1/8'' forward of the belly you can get on an over sized chamber.

[square butte]

Can someone put up a photo of a cartidge case that was fired in a ringed chamber?

[tomme boy]

http://castboolits.gunloads.com/showthread.php?t=81742

Here you go.

[square butte]

Thank you very much Sir. Quite instructive.

[Larry Gibson]

From that thread one can readily see the confusion between a "wad" and a filler". The confusion continues today as too many use the terms interchangeably with out differentiating between the two.

A wad can (that certainly doesn't mean always) cause a ringed chamber.

A dacron wad can cause a ringed chamber.

A dacron filler when used correctly does not cause ringed chambers.

A dacron filler with too fast a burning powder in conjunction with other iinappropriate componant combinations can also cause a ringed chamber.

Point is some "fillers" are quite benificial (I am partial to dacron) and pose no risk of ringing chambers if used with the correct powders and combinations.

Larry Gibson

[geargnasher]

Rings are caused by excessive and concentrated pressure resulting from isolated airspace between the powder charge and the boolit base. Card wads tamped down over the powder leaving space between the card and the boolit are the worst offenders, but Dacron or other fiber fillers will do it as well. The solid or granular fillers aren't really known for actual ringing because they take up all the space between boolit and powder, although they can create their own set of dangerous overpressure conditions in bottlenecked cases if improperly used.

What happens to cause the rings is the powder lights behind the wad and builds pressure very quickly, moving the wad forward very rapidly and with great pressure. Right as the powder is getting going really well and expanding volume, the moving pressure front slams into the fixed obstacle of the boolit base, having had a pretty good head start from the empty space behind the boolit. When this pressure front slams into the boolit base, the presure is deflected outward radially in the area right behind the boolit. Keep in mind the powder kernels in the burning pressure front are still expanding and building pressure as this happens and the deflection off of the base of the boolit concentrates the pressure into a radial ring, which often is enough to stretch the brass and chamber permanently before the pressure equalizes within the case and applies enough pressure to unseat the boolit and get it started on it's way.

If Dacron is used, it should be "fluffed" up between the boolit base and the powder charge at a density that only slightly compresses it against it's natural loft. This will locate the powder positively in the back of the case, keep it from migrating, but will not form a solid pressure piston ahead of the powder like a wad will, or even Dacron if you pack it tightly against the powder while leaving an airspace behind the boolit.

Gear

[emrah]

So is it a bulged chamber then? I looked at the pic from the link provided earlier but it really just shows some striations. Is the chamber wrecked after that?

Emrah

[runfiverun]

it can be.
sometimes you can still shoot it,and remove the case after firing.
other times you cannot remove the brass from the chamber.

[calaloo]

Breech seated bullets are pushed into the bore of the rifle. The base of the bullet is some distance ahead of the case mouth. The case is often loaded with powder and then a wad to prevent powder from spilling into the action during loading. Now you have a definate space between the bullet and the wad. It has been proven that a chamber ring will not occur if the wad is not against the powder. A distance of two tenths of a inch will allow the powder face to "slump" and prevent ringing.

[Gtek]

Ringing usually is from the old days with softer barrels. 32-40 and 32 Miller in this house get a pea of Kapok, breeched, no hint of ringing. Many of the straight wall boys leave between .100"-.200" air gap under .032" or .060" veggie cookie, no ringing. Some use a 1/4" floral foam in case neck just to hold powder and they say protect boolit base. It is all down to powder used and specific load configuration. Everyone of them needs something a little different. Research your load out before stuffing. Gtek

[papertrl]

... A dacron filler with too fast a burning powder in conjunction with other iinappropriate componant combinations can also cause a ringed chamber.
Larry Gibson

Larry & Crew,

I'm considering trying Dacron/Polyfill batting for a filler and have been reviewing old threads on the subject. Would this be one of those inappropriate combinations? 303 British, 215 gr RNGC, 21.0 gr IMR 4198. Might 4198 be too fast for the weight of the boolit to be a good (safe??) candidate for filler?

While I'm asking filler questions, do I understand this correctly: You don't tease your 3/4 gr polyfill batting to be any fluffier? You just work it into the case, leaving it high enough in the neck for the boolit to lightly compress it? Hope this thread isn't too old to be noticed. I'll repost in a new thread if I don't get any nibbles. Thanks for any responses.

Papertrl

[Lumpy grits]

Don't use any filler.
LG

[Doughty]

I would suggest reading up on a guy named Paul Vielle. Or much easier to do, read Chapter 17 B of Charles Dell's book on the Modern Schuetzen Rifle, 2nd Edition for a more insightful look at what really causes chamber ringing. The tales of shooter's wives persist.

[longbow]

You will find filler to be a very controversial subject.

I have used and like Cream 'O Wheat for use in my .303's. I started using filler originally because we have very little in the way of reloading supplies locally and it was even worse a few years ago. I used to shop in Colville Washington for reloading supplies before Homeland Security put a stop to cross border shopping for gun parts and reloading supplies.

Anyway, my goal was to be able to use powders I had on hand that were not necessarily the best for cast boolits. With many powders, downloading beyond a certain loading density can cause problems. Using a granular filler like COW provides a benefit or two in that not only is loading density always 100% but with powders taking up 1/2 or less case volume it ensures you can't double charge as well.

COW also helps protect the base of a plain base boolit too and I shoot mostly PB boolits.

I got my first lessons and answers regarding fillers here:

http://www.303british.com/id37.html

and from contacting David Southall. He was very helpful.

Surplus Rifle also had a good article on using PSB filler for .308. That site is now down but I copied the article so could e-mail it if you would like to read it.

I have shot thousands of rounds now using COW filler with no problems at all though I will stress that I worked up loads using the filler. You cannot just go putting filler into any load. Start with a light charge then increase powder while decreasing filler quantity.

Since you are asking about Dacron filler you may not be interested in granular fillers or PSB but it is another option that can provide good results when used properly.

I have not used Dacron so far so cannot comment though I believe Larry and his results so may give it a go at some point.

Longbow

[hiram]

Seems to happen to straight wall cases.

If I can find my posting with picks, I'll list it.