308 Paper Patch

[geargnasher]

I can see the gap causing the paper rings, I've experienced it a lot too, but there shouldn't be any mechanism going on causing any LEAD to get in there. Something's rotten in Denmark.

Gear

[303Guy]

Did you mention your alloy hardness? It looks to me like your chamber has a fairly sharp step in it - sharp enough to catch and cut the paper and lead as it expands into the case neck/chamber end gap. Just maybe a harder alloy boolit would resist that expansion. You might need to increase the chamber end chamfer. That chamber/throat slug is going to be revealing I'm sure.

[geargnasher]

+1 303Guy. It might be "wadding up in the middle" trying to engrave, pushing paper and lead into the recess at the end of the case mouth and then shearing off a ring as it finally gets pushed completely into the barrel. I've shot some pretty soft lead pretty fast and never had that happen, but is seems that it's possible.

Gear

[MBTcustom]

Perhaps we you are forgetting what causes leading in the first place? Is leading caused by abrasion? shaving?
We know that leading in the bore is caused by gas cutting around the boolit and depositing vaporized lead in the bore. What 161 has going on here is the same thing that happened to me. I had lead in my rings also, and I had no sharp step in the 358Malcolm because I designed the chamber, lead in, and throat, and I cut it myself. Furthermore, I had lead deposited on the necks of my brass as well!
Look closely at this picture and take particular note of the rim:

Whenever gas has the opportunity to get around the boolit, you have a recipe for leading, even if that place is only .025 wide. The paper rings also are made up of vaporized paper. Did any of you fellers ever find ink from your patches on those rings? I didn't. No matter what kind of markings the patch had on it, the ring was an even color. This suggests to me that the ring is made of highly compacted paper dust, just like the lead is made of highly compacted lead dust.
Of course, I could be wrong.

[161]

Did you mention your alloy hardness? It looks to me like your chamber has a fairly sharp step in it - sharp enough to catch and cut the paper and lead as it expands into the case neck/chamber end gap. Just maybe a harder alloy boolit would resist that expansion. You might need to increase the chamber end chamfer. That chamber/throat slug is going to be revealing I'm sure.

Straight WW

[geargnasher]

+1 on the paper-dust theory, Goodsteel, sound reasoning and I've never seen any marks myself either. The question is, if everything from the land origin to the boolit base is covered with paper, how's lead getting abraded without destroying the patch? It can't. There's a major jacket failure going on somewhere between the end of the chamber and the boolit base, right where the jacket is needed the most. On top of all of this, 161 is using COW filler like I suggested, which is a heck of a gas sealant. I've fired greaser .30-30 loads with a gas check and NO LUBE using only poly shotshell buffer. The seal was so good behind the boolits that they didn't lead. Really troubling what's going on here.

How about an impact slug of the throat, 161?

Gear

[303Guy]

Paper and lead being scraped of the boolit could cause it I would think. I wouldn't have thought gas cutting would act so soon and deposit so much in the case mouth/chamber gap. I would have thought that if gas cutting was occurring that early the conditions would be too fierce for deposition yet clearly there is something going on to deposit lead on outside of the case mouth!

I've only ever had paper rings which were clearly identifiable as the tail of the patch.

This one came from inside the neck. Here it is unwrapped but it was a double wrapped ring when I pulled it out. It was the bit that sat over the base rebate on a tail-less patch. A very different scenario.

[Nrut]

A very different scenario.

161 is using 'ball' powder and 7cc of COW..
= no gas cutting..

[geargnasher]

Here's a pic of some of my paper rings. No lead whatsoever anywhere on the cases or in the barrel.



Here's a pic of some loaded rounds in .270 Winchester



A closeup:



All of these have a little gap at the end of the case, but even so the .270 doesn't even leave rings with the 100% cotton Vellum paper. Why this isn't working doesn't make sense.

Gear

[rays308]

I'm still learning this PP stuff myself so please take this only as an amateur observation.

The Lee 170 grain is a bore rider which means the nose is about .300 dia out of the mold. If the rifle throat is pushing the nose back into the case beyond the first band. There could be mis-alignment and possible blowby destroying the patch.

Are both boolits shaving lead?

When I got my Lee 170 FP. The bands weren't concentric with the bore ride portion. When I sized the bands down to .302 I had bands missing on half the boolit. Put one on a shadow box and found the bands .0025 out of concentricity with the bore ride.

[windrider919]

Back when I started converting from BP to Smokeless, I got several rifles that had never had problems shooting PP develop rings.

And several times, shots that kicked unusually hard and had high pressure signs also had rings in the chamber mouth. ( and there was a trace of leading at the muzzle of the rifle...on ONE shot )

Never 'conclusively' proved the cause but working with the idea that either a) the slight crimp I was using was cutting the patch in two or b) the patch was slipping and wadding up around the bullet side (and forcing paper into the gap in the chamber mouth) resulted in changes to my loading procedure and the type of bullet I was shooting...and the rings stopped.

In either case above, the patch was slipping or wadding up as the bullet moved forwards out of the case. I was shooting smooth sided bullets back then...one 'quick fix' was to knurl the bullets with a course wood file/rasp before patching. And I stopped ALL crimping...in fact this is when I started using a larger expander ball in the sizer die to make the case mouth bigger and DECREASE case mouth tension/grip on the bullet. [Ad eventually, in most cartridges, I do not re-size at all, or at most, just run the case a tenth of an inch into a neck die & expand...some not even that!]

And the rings STOPPED!

Hope this history of my ring experience helps.

[161]

These are some of my fired untrimed cases. No sign of blackening.



Guess I don't understand how the boolit and patch pass through a ring of fire when there is COW between the base and the powder.

[geargnasher]

That makes two of us.

The only explanation I have is that the boolit and patch extrude into the gap between the end of the chamber and the end of the case and the end of the chamber bites off the ring when the whole boolit finally moves. IOW the base is being pushed by the filler and the nose is resisting being moved (engraving force) so the boolit flows to fill any space. When the boolit fills all the space and there's nowhere to go but forward, it moves, shearing the bulged ring off of it's "waist". Thats the ONLY explanation I have, although it's pretty far-fetched unless you're using a really soft alloy. Air-cooled wheel weights are good to at least 2650 fps in a .30 caliber, I know for a proven, chronographed fact. Never pushed 'em harder, but the word on the street is that you don't need harder than ACWW until you exceed 2700 fps, and only then to restore a bit of lost accuracy, not because something was failing mechanically.

I don't know what would make your cases longer unless you just keep shooting them, and even then you'd probably have to FL size them each time to get them to grow much. I have '06 brass going on nine full-power reloads that has only been NS'd and I haven't needed to trim it yet. I keep looking for the "dreaded donut" and feeling for incipient case head separation, but no signs yet. Prolly time to trash it anyway, though.

Gear

[MBTcustom]

You could reform 30-06 cases to 308 and neck ream. Then you get what ever length you want!

[303Guy]

To stretch your brass you would need to dry the chamber and cases quite well.

I know my boolits expand into the gap because I catch my boolits. It does not cause a problem most of the time. My alloy is rather malleable though.

[161]

I'll squeeze down some 30-06 brass. Been doing some work around the house.

[bearcove]

If you have a "gap" at the case mouth, when the boolit exits the case mouth the base is unsupported. the nose of the boolit is engaging in the rifling. The unsupported base is possibly obturating and then the "ring" is sheared off as it hits the other side of the gap leaving a ring. If the gap is big you may be cutting all the paper off the corner of the base and some lead too.

Now you don't have it fully patched

[Wolfdog91]

Ttt

[gee-gaw]

Let’s keep this near the top… I’m learning so much here, and would love for some of the more knowledgeable ones to continue this conversation.

[greywuuf]

Love to hear how this is progressing