Ugly Lapua brass

[Tesoro]

I polish/clean my brass after firing using hand drill and 00 3m pads.They come out shining like gold leaf.
I have one chamber job that was not done well and I got concentric ring imprints. We polished the chamber as best as could and now the fired brass comes out looking ok. And then after polishing they shine. BUT after running through f/l Wilson sizer the rings appear again. My Wilson looks smooth inside the bore.
So does the polishing stage camo the ring imprints and somehow the sizing die brings them back to life? Just trying to figure how the die could actually do this. I dont get linear scratches in die - ones in pic if figure come from steel mag lips ( to be polished)

pic: 6xc on left..was shiny but comes out of die like this. 6br on right with normal chamber job after sizing and it was also shined up before sizing.

 

[565tinfitter]

Yes. The rings that are imprinted by the rough chamber are formed into your brass, and made clearly visible by running your cases through your die.

 

[Tesoro]

Answer is to wack the chamber off the barrel and have it re-chambered correctly this time. It is also crooked. Points 14-16 moa off center bore at 40 yds. Burris inserts fixed this and it shoots sub moa at 1000. So it is worth fixing. Just more unnecessary expense and hassle.

 

[jimmymac]

Fire, wipe down, reload, fire. The target doesn’t care about brass appearance.

 

[RegionRat]

If we had your brass in the lab, what you would see is the difference between Ra and PRa, which is roughness average versus profile roughness average.

By polishing, your media follows the contour of the surface and brings it to a pleasing aesthetic roughness average, but that polishing doesn't remove the "profile errors".

When you go back into a die, the peaks of those profile errors are being worked over their shear strength and they yield, while the "valleys" do not. In effect, the die is showing you the tops or plateaus of the profile errors.

Keep an eye on that die and make sure you keep it clean, and/or yes you would re-do that chamber.

 

[Webster]

I polish/clean my brass after firing using hand drill and 00 3m pads.They come out shining like gold leaf.
I have one chamber job that was not done well and I got concentric ring imprints. We polished the chamber as best as could and now the fired brass comes out looking ok. And then after polishing they shine. BUT after running through f/l Wilson sizer the rings appear again. My Wilson looks smooth inside the bore.
So does the polishing stage camo the ring imprints and somehow the sizing die brings them back to life? Just trying to figure how the die could actually do this. I dont get linear scratches in die - ones in pic if figure come from steel mag lips ( to be polished)

pic: 6xc on left..was shiny but comes out of die like this. 6br on right with normal chamber job after sizing and it was also shined up before sizing.





View attachment 1529208

Why all the long vertical scratches? The scratches can only come from high points on the die surface or dirt? I don't know if the rings are chamber roughness? The rings are just the microscopic thickness of Cu oxide rubbed off. They shouldn't be from the removal of metal. I doubt you will see yellow color from galling in your die? Never saw the rings or vertical scratches on my brass. What's your bump set back?

 

[Bc'z]

I'm wondering if polishing your chamber increased the fired brass measurements, and the rings are your die making fat brass skinny agian
Can you compare brass before polished chamber and after, also new brass?

 

[4xforfun]

So...it is only LAPUA brass that does this?

 

[M-61]

How’s it shoot? Sub moa at 1000.
Not sure I’d do anything but enjoy it.

 

[Capt. Oblivious]

wowzers

 

[Tim Singleton]

Why all the long vertical scratches? The scratches can only come from high points on the die surface or dirt? I don't know if the rings are chamber roughness? The rings are just the microscopic thickness of Cu oxide rubbed off. They shouldn't be from the removal of metal. I doubt you will see yellow color from galling in your die? Never saw the rings or vertical scratches on my brass. What's your bump set back?

long scratches maybe magazine fed?

 

[Webster]

long scratches maybe magazine fed?

Looks like at least 50 scratches. They go all around the case? If you chamber a round and extract it without firing does it have the rings and scratches on it? Try to narrow down when it happens.

 

[Tesoro]

long scratches maybe magazine fed?

this answers all the comments above, except that the guy who did my chamber job didnt chamfer the entrance so I got scratches from this before we fix it.

 

[Dave M.]

Better question might be “what is going on with those necks??”

 

[Tesoro]

Better question might be “what is going on with those necks??”

good eyes..i was waiting for that! those are 308 palma cases wildcatted into 6xc. makes 2 ridges in the neck as part of process but they are cut, reamed and turned. leaves 2 brown scars. It is a Tubb chamber so the fired necks are .278 and are squashed down to .268 which leaves a bulge, but past the seating area. Once fired it disappears until next neck bushing work.

 

[Tesoro]

How’s it shoot? Sub moa at 1000.
Not sure I’d do anything but enjoy it.

I cant! everytime I process cases the evidence of an amateur job re-appears and pisses me of. So I am going to chop it and have it re-done by a non-amateur!

 

[Tesoro]

I'm wondering if polishing your chamber increased the fired brass measurements, and the rings are your die making fat brass skinny agian
Can you compare brass before polished chamber and after, also new brass?

pics are new brass. didnt polish chamber enough to affect the spec chamber dimension per fired brass measurements. If we had then would have got rid of the scars and i would have wound up with over expanded cases. Not.

 

[Bc'z]

pics are new brass. didnt polish chamber enough to affect the spec chamber dimension per fired brass measurements. If we had then would have got rid of the scars and i would have wound up with over expanded cases. Not.

I got some necks that show the rings, but I know I'm squeezing the hell out of them

 

[Ledd Slinger]

This same exact thing happened

I polish/clean my brass after firing using hand drill and 00 3m pads.They come out shining like gold leaf.
I have one chamber job that was not done well and I got concentric ring imprints. We polished the chamber as best as could and now the fired brass comes out looking ok. And then after polishing they shine. BUT after running through f/l Wilson sizer the rings appear again. My Wilson looks smooth inside the bore.
So does the polishing stage camo the ring imprints and somehow the sizing die brings them back to life? Just trying to figure how the die could actually do this. I dont get linear scratches in die - ones in pic if figure come from steel mag lips ( to be polished)

pic: 6xc on left..was shiny but comes out of die like this. 6br on right with normal chamber job after sizing and it was also shined up before sizing.





View attachment 1529208

This same exact thing happened to me when I used a hand drill and steel wool to give brass a high polished finish.

The issue is that you are simply polishing the surface of the brass too much. The brass being spun at high speed in an abrasive pad causes the surface to become way too smooth. The surface of a sizing die also has a very smooth finish. The mating of two super smooth surfaces causes excessive friction and galling on the brass in the die when you size the case. All of those lines are brass being scraped off and left on the wall of your FL die. It will keep building up in the die and get worse the more you size the cases without cleaning the die. And unfortunately, it's not very easy to clean off the walls of a die.

If you want clean cases after every firing, just run them in a media tumbler and nothing else. I know the brass is pretty when polished really bright like that, but trust me from my own experience, that if you keep polishing the cases at high speed in a drill with 3M pads, you will continue to have this issue. A very smooth metal surface on another very smooth metal surface is not a good thing. Don't want too high of a polished finish on a chamber either.

Cylinder walls in engines are finish honed in a cross hatch pattern so they have less friction and wear on the rings, but it also creates tiny pockets on the surface to hold oil on the walls for lubrication. With two extremely smooth surfaces on your brass and FL die, you are also greatly reducing the effect of your sizing lubricant because it has no space to squeeze between the surfaces.

 

[Webster]

I polish/clean my brass after firing using hand drill and 00 3m pads.They come out shining like gold leaf.
I have one chamber job that was not done well and I got concentric ring imprints. We polished the chamber as best as could and now the fired brass comes out looking ok. And then after polishing they shine. BUT after running through f/l Wilson sizer the rings appear again. My Wilson looks smooth inside the bore.
So does the polishing stage camo the ring imprints and somehow the sizing die brings them back to life? Just trying to figure how the die could actually do this. I dont get linear scratches in die - ones in pic if figure come from steel mag lips ( to be polished)

pic: 6xc on left..was shiny but comes out of die like this. 6br on right with normal chamber job after sizing and it was also shined up before sizing.





View attachment 1529208

You said the rings appear after sizing. Try more lube or a better lube. I use a low vis synthetic hydraulic oil I get from AutoZone. It wouldn't hurt to over lube a few cases to see if it helps. Clean the dies after to remove excess lube buildup. I would guess that the case is slightly grabbing in the die, releasing then grabbing again at a level you cannot feel. Sorry if I am repeating something from other replies. I don't always feel like reading a long list of replies to answer properly. Looks like there is more rubbing off of the copper oxide layer at the .200" level by the case head. This is the area that probably gets the most sizing. This part of the case is outside the chamber so the extractor can grab it. The scratches are more puzzling.