Paper rings...again

[dubber123]

I just read through the thread on paper rings left in the bbl. I still have questions. I just started paper patching for my 50-90 double rifle. I made the mould myself, and it is smooth sided, weight is 560 grains. Boolits are 50/50 WW-pure by volume. They seem to be shooting well, (I'm still regualting the rifle), but twice now I have had a 3/16" long ring attached to a fired case. This ring looked like a bunch of the patch had wrinkled up and torn off. This can't be helping consistancy.

The brass is not short. In fact the most exposed paper I can leave is maybe 1/16". Any more and it bunches up on the throat. Groove is .510" Patch diameter is .511+". Will knurling or roughening up the boolit help the patch to not slide down the boolit when transitioning from case to rifling? Thanks for any info.

[303Guy]

First off, I am waaayyy to new to paper patching to answer you, but, I have had the same thing, a little ring of paper stuck to the case mouth - better than having it stay in the chamber! Is your boolit a bore rider or tapered? (I am thinking of a design with a taper from the ogive to just before the seating shank where I want it parallel for good seating reasons). Have you got pics of you boolit? And mold perhaps?

[dubber123]

Nothing elaborate, just a straight sided, bore ride design.

[docone31]

I have always suspected, the paper ring is the area between the case mouth, and the rifleing. Literally, the pressure of fireing extrudes the paper as well as obturating the casting. The ring is paper that is sheared off and it fills the gap.
In other words, the termination of the case mouth to the beginning of the rifleing, there is a little gap the thickness of the of the space. The chamber will be the same diameter to the rifleing entry. Where the brass ends, the patch is smaller in diameter than the outer limits of the case.
It makes an hard ring of paper.
Kinda like an O-ring.

[dubber123]

It is very short from the end of the case to the start of the rifling, almost no room for a full diameter front drive band. This is one of the biggest reason to go with the bore ride design, as almost none of my other moulds would fit without deep seating the boolits.

Perhaps a gentler leade into the rifling would help, but I'm not ready to start monkeying with my chambers now that I have it on the run, so to speak. I am hoping that giving the patch something to grip onto on the boolit sides will help tha patch make the transition.

[Lead pot]

A short case will cause you paper rings and lead rings.
But in your case I think it starts when you feed the round in the chamber when you say it's wrinkled.
Most chambers now days have a 45 degree chamber end before the lead starts and that will catch on the jacket and pushes it back with your patched bullets that are at groove diameter and in your case it is over groove diameter.
Most PP chambers in original chambers had a tapered free bore lead and not that 45 degree chamber end with that long tapered free bore to groove diameter made a smooth transition into the lead.
A PP bullet with the chambers now made are not the best for patching a bullet to groove diameter.
I read a lot on this forum with you guys Patching your bottle neck military rifles to groove diameter and over that tells me that you are seating that bullet way deep in your bottle neck case down past the case neck into the shoulder of the case that is death with a PP bullet, because the bullet upsetting before it starts on it's way down the barrel and when that bullet swages back down to thew case mouth diameter it strips the patch off at the point where the case neck starts and also spikes the chamber pressure.
I know some will say that smokeless powder wont upset a bullet, well your wrong it will upset a copper jacketed bullet too.

[Lead pot]

Dubber I for got to mention.

Fully chamber one of your rounds once and extract it with a cleaning rod if yo have to and look at your patch and see what it looks like.
If your putting a crimp on the case mouth even a slight one that just holds the bullet from falling out , that slight crimp will cut the patch when it gets fired and cut the rear portion of the patch.

[dubber123]

Dubber I for got to mention.

Fully chamber one of your rounds once and extract it with a cleaning rod if yo have to and look at your patch and see what it looks like.
If your putting a crimp on the case mouth even a slight one that just holds the bullet from falling out , that slight crimp will cut the patch when it gets fired and cut the rear portion of the patch.

It wrinkles/cuts the patch. The distance from case mouth to the 45° taper is so short, I can leave at most, 1/16" of paper showing. I have just been trimming flush with the case mouth for simplicity. I just knurled a few boolits, and will see if that helps.

I basically just straighten out the bell, no crimp. I made a die with the chamber reamer, and use it as a sort of taper crimper to iron out the end of the case.

[felix]

It will also upset the barrel as everything else expands. ... felix

[windrider919]

dubber, then your patch does not extend beyond the cylindrical bullet side and onto the nose ogive? The patch is supposed to cover all the bullet surface that could touch the barrel. The best seating depth is when the rifling just touches the bullet, the case mouth just grabs the PP bulet snugly without damaging the patch.

next, what diameter is the bullet without a patch?

And what is the throat diameter in your chamber, how much clearance between the PP and the throat. If it is too small it could be catching the patch and pushing it backward.

I do not think you should be trimming the patch close back to the case mouth, then what centers the bullet if it is slightly cocked in the throat. If the bullet is touching the rifling that will center the bullet but if not the patch works to center.

I too had problems with rings but found it was too long a chamber. had the barrel shoulder set back .020 (twenty thou) and a better finish reamer used to make a tighter chamber. No rings now.

[docone31]

That is what I figuired also.
When I patch, I bring the patch up to just where the nose begins the transition to the sides.
It does take some tweaking to make a good patch. Once it is there though, I never went back.
It did take some tweaking.

[405]

I have always suspected, the paper ring is the area between the case mouth, and the rifleing. Literally, the pressure of fireing extrudes the paper as well as obturating the casting. The ring is paper that is sheared off and it fills the gap.
In other words, the termination of the case mouth to the beginning of the rifleing, there is a little gap the thickness of the of the space. The chamber will be the same diameter to the rifleing entry. Where the brass ends, the patch is smaller in diameter than the outer limits of the case.
It makes an hard ring of paper.
Kinda like an O-ring.

Yep, that is the way I think it happens also. It seems to be more common in those chambers that are not stepped between end of case mouth (chamber end) and entry into bore... there is a taper between end of chamber and entry into bore. I've seen quite a few of the older (original BP guns) with that tapered type of throat. Of course the other condition that has been known to leave the paper ring is the short case in even a modern style, stepped throat. There may be other causes but the tapered throat or the too short case seem to be the most common.

[Lead pot]

405.
I'm a little confused on the stepped throat you mentioned.
I never seen a step in the throat, can you explain what a step in the throat is?

[405]

Nothing more than a conventional, modern style throat. The "step" begins as a fairly sharp transition between the end of the chamber at the maximum theoretical end of the case mouth (beginning of the throat). Then in an ideal world that throat diameter will be about the same as the groove diameter and continue into the bore to where only the leading edges, entry into the lands are tapered. In many of the older style (BP era) throats I've looked at there is no sharp end to the chamber at the beginning of the throat. The full diameter of the chamber at the end of the neck (case mouth) is tapered on into the bore. That leaves a "wedge" shaped free bore that will always be larger than the bullet diameter immediately ahead of the case mouth. Since that wedge shaped space is available, it is theorized that a paper patched bullet, as it is obturated (mostly at the base) at the beginning of it travel forward, will fill that space and "nip" off the paper ring in question.

The same thing can happen if a case is too short in a conventional, modern style throat which leaves a parallel sided space (not wedge shaped) where the PP bullet will try to fill by obturation before entering the throat... likewise leaving a paper ring.

Even when cutting conventional, parallel sided throats the throat portion of the reamer or the separate throat reamer can be oversize and leave a throat diameter quite a bit larger than groove diameter. Again this is a headache for most cast bullet shooters and must be taken into account when sizing bullets. But the chamber dimensions in the neck and the wall thickness of the case can limit bullet size compensation. It would likewise be a problem for a paper patched bullet.

Sure would be easier to show a schematic than explain with verbage The differences show very clearly in chamber drawings of the types of throats.

All the possible causes of leaving the paper ring after firing may be best guess, but deductive reasoning suggests that the two (possibly three) mentioned are reasonable guesses, I guess.

[dubber123]

405 makes a pretty good description of what my chambers look like. Mine has a VERY short cylindrical area just in front of the case mouth, followed by a 45° taper into the bore. My bbls. slug at .501" bore, (prolly a little looser at the breech end, as it has tapered bores), so I am sizing to .501". I have enough boolit that it is well up in the bore for centering when chambered.

I get the slightest hint of engraving on the boolit noses, for about 5/16" on the sides. I can't leave any paper at all showing, as it will bunch up and tear when chambering. It makes chambering hard, extraction too. Accuracy seems to be fine, I just don't want the rings possibly causing flyers, so I want to eliminate them if possible.

[montana_charlie]

There is a long discussion here ( http://castboolits.gunloads.com/show...ighlight=leade ) about the internal topography of a rifle barrel. It has pictures, and shows how things like chamber step, freebore, and leade form the launch pad for a cartridge.

There was an attempt to agree on a rational way to describe a chamber using traditional 'names' for the various elements. But LG insisted that only the terminology used by 'a respected gunwriter' was appropriate...and only when used in the way he (that writer) uses it.

So, while you may wish to disregard the 'terminology' part of the thread, the pictures do show that 45 degree chamber step.
CM

[dubber123]

I just tried to chrono 2 more. I missed the front lens with the first shot, the second recorded over 3,300 fps. Hmmm, not bad for a 560 gr. 50-90..... I'm guessing the muzzle blast reached the screens before the boolit. I had the same problem with my 50-70. I had to back way off. BTW 1 of the 2 had 3/4 of a paper ring left attached to a case.

[45 2.1]

Make sure the patch goes onto/over the boolits ogive enough so it doesn't peel the patch back when chambered. You do NOT want the patch just on the parallel portion of the boolit, it needs to go onto the nose some also. Seat the patched boolit so a fouled bore will make dirty marks on the patch from the lands at the rifling origin when chambered.

[405]

Yep for every detail there will be a few different terminologies used. Sorry about the confusion over the different parts of a throat.

Yes, there is a good side to paper rings.... you can see and identify them.

The only time I can get rings left on the case mouth at will is by shooting a grease groove paper patched bullet thru an old style tapered throat. In all other instances they show up at random if I goof up or experiment a little too much.

Paper patching adds another variable to the cast bullet scenario. It can get frustrating when the so called flyers out number those that stay in the group and there is NO evidence left over with which to work on a solution. Then it can become tedious.... changing one variable at a time until by process of elimination the culprit is found. I have no doubt that in some PP loads that don't act right there is a ring or hunk of paper torn off during the transition from case to full bore engagement but there is no evidence left... just errant bullet flight. The paper shred (evidence ) is blown out the bore with the rest of the powder gases, solids, lube, wads and bullet.

But, on the other hand when things are put together right, a paper patched bullet over BP will shoot! Some of the best groups I've ever shot out of the Sharps or RB rifles have been shot with swaged, paper patched bullet over BP.

[dubber123]

Make sure the patch goes onto/over the boolits ogive enough so it doesn't peel the patch back when chambered. You do NOT want the patch just on the parallel portion of the boolit, it needs to go onto the nose some also. Seat the patched boolit so a fouled bore will make dirty marks on the patch from the lands at the rifling origin when chambered.

If you study the shape of my boolit in the pic, you will see anything over the ogive is impossible. It is bore diameter right up to about 1/4" from the nose. I have only shot it a little at 75 yds., and some plinking at 100 yds. I didn't notice any flyers, so maybe I am worrying over nothing.?

Being it is snug in the bore, it should be guided well. If even a random, (but sufficent) amount of patch stays on each boolit to seal the bore, perhaps it won't matter? Each bbl. shot around 2" at 75 yds., and that is with the poor triggers, and a so-so rest. Maybe my knurling will hold it to the boolit enough to at least minimize the rings.

It sounds as though re-throating to a differnt style might help, but unless it is patched over the ogive, I might never succeed in eliminating the rings.