Sheared pressure ring?

R.G. Robinett said:
Roger this . . .

The [so called] pressure-ring, is normally about 0.0003" to 0.0004" over the nominal bullet diameter, thus, even if the P-R could/did shear off, at best, would be only about 0.0002" 'THICK' - <1/10th the thickness of a human hair.
Residing in the fire-blast zone, its difficult to imagine that the ultra thin gilding metal wouldn't have been vaporized, and possibly deposit along the bore . . . ????:confused: Surely, this is a weird one.:eek:RG
Click to expand...

Is it possible when seating the core to apply enough force to stretch or weaken the jacket at the pressure ring/heal of the jacket? Maybe somebody threw a set-up bullet in the pot when they were made? Or maybe the punch when forming the jacket might have had too sharp of a corner?
 
Last edited:
Rflshootr said:
Is it possible when seating the core to apply enough force to stretch or weaken the jacket at the pressure ring/heal of the jacket? Maybe somebody threw a set-up bullet in the pot when they were made? Or maybe the punch when forming the jacket might have had too sharp of a corner?
Click to expand...

Did you see this from firing one bullet or was it cumulative from all 15?
 
Rflshootr said:
One thing I might add is that the reamer has zero free bore with a 1.5° lead. I don't think that is the cause because I chambered 2 other barrels with that reamer and haven't had an issue from either one of them. The only thing that I can come up with is a bad jacket for whatever reason. So far that is the only thing that seems plausible to me.
Click to expand...

I don't know what you have there but a 1.5° is the same as 1°-30 minutes and it's by far the most commonly used throat angle out there in the br world. I doubt that's got anything to do with whatever that is.
 
antelopedundee said:
Did you see this from firing one bullet or was it cumulative from all 15?
Click to expand...

I can't honestly answer that. I hadn't had any problems until I was testing a new powder in the rifle. I loaded 15 rounds with increasing powder charges with a known good seating depth from previous load development. Just so happens that it spit the last round at which point I was going to clean anyway. That's when the copper ring came out of the chamber. So I can't honestly say if it was an accumulation or from the last round. But if I had to guess, judging from the last 100 rounds with almost no copper fouling, and from fair to midland groups with the new powder, everything seemed normal until the last shot that went 2" high out of the group. Up until that point I had no reason to suspect anything was wrong. Then I ran the 1st wet patch down the bore at the range and felt a ton of resistance and was like...WTF?
 
Last edited:
Rflshootr said:
I was working up a load with a new powder (Sta-Ball) for a 7-08 with some old lot 120 Sierras, made in California, and after 15 shots I cleaned to switch powders, and on the first patch, this came out. Shot these bullets with other powders and no problems. I called and emailed Sierra and they told me that no one there has ever seen this happen. Anyone ever seen anything like this before?

View attachment 25549
Click to expand...

No. I have never seen that before. Next question.
 
Rflshootr said:
I can't honestly answer that. I hadn't had any problems until I was testing a new powder in the rifle. I loaded 15 rounds with increasing powder charges with a known good seating depth from previous load development. Just so happens that it spit the last round at which point I was going to clean anyway. That's when the copper ring came out of the chamber. So I can't honestly say if it was an accumulation or from the last round. But if I had to guess, judging from the last 100 rounds with almost no copper fouling, and from fair to midland groups with the new powder, everything seemed normal until the last shot that went 2" high out of the group. Up until that point I had no reason to suspect anything was wrong. Then I ran the 1st wet patch down the bore at the range and felt a ton of resistance and was like...WTF?
Click to expand...

Looks to me like an accumulative thing. Maybe load a couple more and clean after each shot. A tight patch with 90% rubbing alcohol would be sufficient. It doesn't appear to be something that one would predict would happen.
 
Rflshootr said:
It appears to be one piece. But with pressure, I guess it could be welded together. Don't know. It came out just like you see it on the 1st patch with Butch's Bore Shine. Hey what a great advertisement that would be for removing copper. ;)
Click to expand...

Maybe if you break it apart , you could see if it's an accumulation or one piece. I've had some fat bullets that didn't like a fresh sharp chamber. Just looks like something that might accumulate in the gap. That's not even a SWAG, just a WAG.
 
I kind of did that, except I just bent it a little to see if any pieces would flake off.
They didn't. If you look at the picture, you can see a round narrow section from about 10:30 to 11:00. It actually is almost perfectly round and actually looks like a piece of solid electrical wire. I've never made a jacket, but now I'm wondering if they may use some sort of copper wire to set up the punch clearance to the bottom of the cup.:confused:
 
Last edited:
About the motorised case trimmer :

I am used to convert 5.56x45 or 223 to 5.45 x 39. Having an AK outshooting DanielDefenses and JPs AR15 in IPSC-R is quite a bit of fun.

This implies at one stage a heavy trimming, done with a piloted mill bit fitted on a drill press. In this operation, lot of chips and heavy burrs are created, outside and inside the neck.

It happens from time to time that I recover a "free" O'Ring shaped burr inside the case. That was an internal burr pushed down, cut to free and propelled inside the case during the trimming operation.

Furthermore, at manually cutting the internal burr, it happens that it get "on air" and pushed down by the deburring tool, and fall into the case. More often with the vld 30° deburring tool.

And what you are showing on the picture looks like .... you guess what.


Of course, should you have the same 10 cases batch shot 14 times already, the above doesn't stand. Should that occured using some new cases or some freshly trimmed cases ...


I also suppose there is no crimping. Crimp area separating from the neck also occured to me, several times.
I also suppose there is no too long a neck, bumping on chamber end at bolt closing and creating both an undue crimp and a pressure bump, as you noticed nothing like that.


I have been in the ammo industry for years and I do not believe you had an issue with 1 jacket. What could have occured 15-20 years after manufacture is a brass seasonal crack, but I never saw it or heard about it on bullet jackets, which are usually not brass alloy.


Anyway, it's very easy to know if the material comes from a case or a jacket or several jackets. Have it microscoped, that will say if it is composite or homogeneous. Have it X ray chromatographied you will exactly know what it is made from. Maybe somebody in this community can do that. Any university with a metallurgic dept will enjoy the game.


Sorry for my poor english scratching your eyes. I am not on the right side of the pond but a way too old ****************************************************************************************************************************************************************ed to find a spell checker here. Neither did I knew you are used to chamber your barrels with all due precautions and borescope it on a regular basis all way down from chamber to crown.. As you wrote, just trying to help.
 
OP,
As OliveOil stated.....

You de-burred a burr from inside of the case neck into the case.

Tumbling the cases would have removed it.

Loading & firing the case...removed it.
 
Dans40X said:
OP,
As OliveOil stated.....

You de-burred a burr from inside of the case neck into the case.

Tumbling the cases would have removed it.

Loading & firing the case...removed it.
Click to expand...

I never realized that gunpowder and pressure turned brass into copper, and that trimming .002 off a case mouth can cause such a large burr.
I learn something new every day.
 
Rflshootr said:
I never realized that gunpowder and pressure turned brass into copper, and that trimming .002 off a case mouth can cause such a large burr.
I learn something new every day.
Click to expand...

Would you please explain to me how one distinguishes "brass" from "copper"?
 
alinwa said:
Sounds like you have it all figured out :)
Click to expand...

what? that he has a brain, a heart or his way home ? It's a good thing guys are off to see the wizard, The Wonderful Wizard of Oz !!! If I remember correctly, the Oz was a short little stubby of a guy standing on platform to reach the mic ! I better stop being a troll. otherwise I might get zapped.
 
Last edited:
As I understand it, Sierra passes its bullets through an additional die that irons out the pressure ring. They do this to make there bullets function better in automatic loading machines. This information was from a long time back, so you might want to ask them if it is still the case. Using my .0001 micrometer, I always check bullets' dimensions including any pressure ring, which gets tricky, but I have learned how to measure them without flattening.
 
You must log in or register to reply here.
Back
Top