Of bullets and things

[Kenny Wasserburger]

MD,

I chamfer my PP cases, and don’t get paper rings, with a proper case length. And this isn’t speculation I shot 1000’s of them.

However a case .003 short of the chamber stop will certainly give a paper ring left on the case mouth.


You need a new theory.

Kenny Wasserburger

[mdeland]

Thanks for that valuable info Wasserburger , it helps in determining cause and effect on some of these interesting questions.

[semtav]

Kenny
When you get to working with that dual diameter bullet, don't be surprised if you find things a little different.

Im still not sure whats going on with my 45 2 7/8 that is shooting so well but every time i reload i have to run an expander die in the mouth of my shells to take a light crimp out so i believe the brass is hitting that angle. Yet when i measure the brass vs the chamber cast it shows its well short of optimum length.

I don't know, since im patching to groove if my bullet is pulling the brass forward and sealing the gap before it moves or what, but its working and l haven't seen any paper rings.

Not saying that will happen but its possible.

[semtav]

Too late to add to my other post but it's also possible that I'm just mismeasuring and I am camming my brass into that angle

[Kenny Wasserburger]

Brian,

That is very interesting. It’s possible that the paper is rough enough to grab the case and pull it. Especially patching to Groove. Make sure your necks are smooth and clean is about all I can offer,

Kenny Wasserburger

Ps. You are right the dual diameter bullet may negate the ring issue entirely. It’s a interesting question. Hopefully I hear soon from BACO.

[bruce m]

mike,
so where does that leave the experiments done by metford and mann, independantly of each other, many years apart, and in different countries.
what they did was drill a hole in the side of a barrel where the bullet sits when in battery.
this hole was threaded, and a rod screwed in the hole.
inside the barrel the rod had a point on it, so that it could be screwed in just short of the bullet in the female part of the rifling. (groove.)
they knew where the bullet sat prior to firing the shot by measurement., so they knew where the point would stick in the bullet when it bumped up if it had not moved yet.
sure enough both found the mark right where the spike was prior to any forward movement of the bullet, which was the starting point of the scratch left by the spike.
we know metford used hardened alloys, and certainly of latter times included antimony in the mix.
one would assume mann also used hardened bullets, because he was from a later time.
add this to things observed by modern shooters like kurt who have produced a plethora of photograpic evidence, and others who have studied their confetti, and dragged paper or lead out of their chambers.
as for cases causing rings, yes this can happen.
however those who have success would tend to agree on some form of case mouth preparation.
the biggest danger with paper patches from case mouths is having no chamfer there as the bumping up led pressing the paper over a right angle would act like a paper cutter.
if you are shaving enough lead (any at all) when seating bullets to cause a problem it is time to go back to primary school and learn how to load ammo.
bruce.

[mdeland]

Not sure how any of that proves bump up is complete in the throat. Wasserburgers and Kurts eye witness accounts of their experiences on the rings of lead and paper give a lot of weight to answer the question we are addressing. I was suggesting some other possibilities to explore.
Didn't Mann do some experiments on bump up that found it was actually completed several inches up bore ?

[semtav]

mike,
so where does that leave the experiments done by metford and mann, independantly of each other, many years apart, and in different countries.
what they did was drill a hole in the side of a barrel where the bullet sits when in battery.
this hole was threaded, and a rod screwed in the hole.
inside the barrel the rod had a point on it, so that it could be screwed in just short of the bullet in the female part of the rifling. (groove.)
they knew where the bullet sat prior to firing the shot by measurement., so they knew where the point would stick in the bullet when it bumped up if it had not moved yet.
sure enough both found the mark right where the spike was prior to any forward movement of the bullet, which was the starting point of the scratch left by the spike.
bruce.

Its too bad they didnt put that spike just barely sticking out in the gap in the transition area so they could see if the lead flowed into it the whole way or just what was over it when it initially bumped up.

[Kurt]

Bruce,
Back about 15 years ago there was a thread like this here just how far a bullet moves before it obturates so I had to see this my self.
I swaged some cores like wad cutters for my .40-70 but I did not drill a hole through my barrel I drilled a 1/8" hole through the cases I didn't want to ruin a good shooting rifle and I patched them and just a bare lead core. The bare cores were very undersized in the case but a taper crimp held them inlace. I put a scribe at the case mouth on the bullet for reference so I could measure from the case mouth to center of hole.
I found the bullets patched left cut paper in the hole in the case and the same with the bare lead slugs. The distance from the scribe line at the case mouth and center of the hole varied slightly but less than five thousands as close as I could measure.
I'm sorry to say the written results are lost.


Brian,
Those two bullets together I cant give you much information, they were sent to me with instructions how they were to be loaded for testing wad stack loads and alloy.

IMG_0070.JPG

[semtav]

Kurt.
Two different scenerios.

1.initial bumpup mostly fills the transition area with lead/paper and then it is swaged back down as it comes out of the transition but that is the only lead/paper that enters the transition area. Once the bullet begins moving, no more enters it.

In this case, bullets that were barely seated in the case would have most of their damage
near the base of the bullet and the gap would be more critical than ones where the bullet was seated deep.

2. lead flows in and out of the transition area the whole length of the bullet that passes over it.

In this case the more damage would be done to a deeper seated bullet than one shallow seated.

My initial question. was not what happens on initial firing, I can see lead/paper filling every void if the lead is soft enough, my question was, what happens to the bullet after the initial bumpup.

paper or lead rings only prove to me it goes in the transition on initial bumpup, not what happens afterward.

[powderburner]

In my 2&7/8 i can get a paper ring on call.
With a standard chamber and fit brass to it when i use 2f or hotter powder it will ring every time.
When i use 1f and a good wad stack i dont get any rings.
I also have some thick wall brass which measures the same od as my id in the chamber and patched bullet id inside which does not leave paper or lead.
My thought on the brass was to get it so it didnt move when fired. My bullets are bore diameter so there is no need for release. The bullet does not expand in the case and i dont see any wasp waist bullets like kurt sees. I think with my dimensions the bullet is past the transition before it bumps.
The bullet alloy is 11 # lead to 12 oz tin apothecary.
There is enough taper on the cases and the pressure is low enough i have no problem with chambering or extraction
I have no idea why it works but it does.
The thick brass is probably the same thing as a dd bullet just a different approach.

[martinibelgian]

I would be very surprised if the bullet would have accelerated enough to reduce pressure below the elastic limit of the alloy. Pressure drops with the increase of volume created by the bullet moving forward, so then we get into lots of variables. But as to whether half an inch of forward movement together with the continuing pressure buildup will already reduce pressure enough to stop bumpup, I really doubt it.

[mdeland]

Do the paper or lead rings translate to inaccuracy that any of you can tell?

[Kurt]

Brian,

If you look at Bullet #1 that bright ring is what gets sheared off. Take a close look at that bullet ahead of the bright ring you will see the ring of the case mouth. This should be a close estimation on how far that bullet moves before the mass gets pushed in the void between the case mouth and the 45º transition. Now mind that that photo is largely increased in size.
All of this stuff figuring it out is not my line of work, I was just a plumber but I know how to work with lead and how to expand it to make a tight connection and seal so water don't leak out

The question, what is the damage to the base???
None that I can see these were fired in a standard Shiloh chamber The GG was shot with the .50-2.5 and the PP in the Shiloh .45-70.
Like I said fit the case to match the chamber as close as you can swith out the case getting pulled up into the throat so you don't get the belled in case mouth like you said you were getting. That will do more damage to the bullet than it getting pressed into the void between the case mouth and that 45º chambered wall.
That is something you don't get with a lead bullet transition.

IMG_2285.JPG

[bruce m]

kurt,
drilling a hole in the case shows 2 things.
first that there is more than 1 way to skin a cat.
second you have a very fertile mind.
brian,
thank you for clarifying your question that i had obviously misunderstood.
firstly, i cannot sy whether the alloy fully fills the transition.
it could but might not.
this of course would depend on the strength of the powder charge, the potential cushioning of wadstacks, etc.
obviously kenny's wadstack could soften the blow and that could explain why his 2 7/8 shoots so well.
there is talk that pressure causes bumpup.
in my own mind it might be pressure, but i wonder if there is a sudden shockwave that preceeds pressure.
why i think this is that a bore diameter bullet with just a card wad will obturate and seal the bore, showing no burn marks or carbon stains on the confetti.
should this be the case, the reason for a rig only is clear.
the bumping of the bullet into the transition only happens when the shockwave hits the bullet, and after that it retains its shape
other than squeezing down where necessary.
of course after the bullet starts to move there is less inertia to resist pressure also.
when i shoot breech seated bullets with an1/8" airgap, i get less bumpup evidence in my confetti, than a bullet seated on the wad in fixed ammo.
looking down the barrel at the breech seated bullet i can see light coming through the gaps where the grooves are.
until that wad hits the bullet and bumps it up there is no gas seal, so there is no pressure.
then something bumps the bullet up fast enough to form a gas seal.
this leads me toward the shock wave theory.
without the airgap the shock is more sudden and pronounced.
so with fixed ammo, and the bullet over the transition, the shock could bump a ring into the transition, the bullet seals at the same time, the bullet starts to move shearing the ring, and no more bumpup occurrs.
yes it would have been interesting if metford had put a spike into his barrel at the transition at this point and fired shots with different length spikes.
bruce.