Chamber issue?

[Andy Work]

Do these marks on the brass indicate a chamber issue? This is once fired brass and when ran through a sizing die it has a quite a bit of resistance and skipping but the brass comes out smooth and sized properly but with these rings. Is this a chamber issue that is brought to light after sizing? View attachment 1415978

I recently experienced that same thing for the first time. Hornady 6mm CM brass, Imperial lube and Redding body die. It felt like a lube problem while sizing, but it's the same method I use on other cartridges which has always worked fine. I don't see any roughness in the die but I may polish it anyway.

 

[tthomp302]

Your die is polishing the ruff brass from your chamber. That chamber finish is awful and i bet you can see it with a flashlight- no borescope necessary

If all my brass is shot through that chamber already, will the rings have a negative effect on my brass? I will be getting the chamber fixed so future firings are better.

 

[Dusty Stevens]

If all my brass is shot through that chamber already, will the rings have a negative effect on my brass? I will be getting the chamber fixed so future firings are better.

No itll be fine and smooth out in a couple sizings

 

[tthomp302]

No itll be fine and smooth out in a couple sizings

Thanks, would have hated to have to trash 200 pieces of alpha brass. I'm getting a borescope in the next few days and will post pictures. I guess I'll just size them as is since they will all be that way for this sizing.

 

[Jim D]

Yes, a bore scope will solve your question.
I have an inexpensive Teslong that works quite well.

 

[hockeyref]

I have a couple new unfired and unsized starline .556 cases that look like this. I assumed it was an artifact from the drawing and forming process and i set them aside to maybe play with later.

 

[tthomp302]

So got my teslong in and was able to get a look in the chamber. I believe I found the culprits. Sorry if they’re not the best pictures.

 

[Will Henry]

chamber sucks...technical term

Well put, and accurate. WH

 

[Kurz]

Maybe not the best pictures but they tell the story of what is wrong with your chamber and therefore answers your question. Have your gunsmith polish the chamber carefully.

 

[6.5 forever]

That looks kinda rough. Good luck getting it finished.

 

[STS]

My experience with that type of flaw in a chamber is that it's extremely difficult to eliminate the problem. When you go at it with some wet or dry paper and some oil, the abrasive is cutting just as much in the bottom of the defects as it is on the top of them. You have to use a cutting tool to remove just the high spots, which is not really doable with paper. You end up with the same marks in your brass as before just slightly less obvious.

 

[Webster]

Do these marks on the brass indicate a chamber issue? This is once fired brass and when ran through a sizing die it has a quite a bit of resistance and skipping but the brass comes out smooth and sized properly but with these rings. Is this a chamber issue that is brought to light after sizing? View attachment 1415978

Many guys love Imperial sizing wax. Could be some combination of chamber size, case size and die size meaning you have to squeeze the case in the die more than normal. You said you had to use a lot of force to size the case and you get what feels like chatter. This chatter must be the die grabbing and releasing the case due to poor lube. This would explain the rings. A chambering reamer doesn't stay in one place and rotate, it move forward and back out producing a cross hatch tool pattern? You said the rings don't appear after firing only after sizing. That alone should answer your question. Maybe Imperial isn't good enough for cases that are very tight in the die? I worked in the petroleum industry. I still think a petroleum type oil is the superior lube. I bought a quart of low vis petroleum oil based Hydraulic fluid at AutoZone for $8.50. It doesn't stain the cases. I roll the cases on a pad. I have been using it for several years. Pet oil has superior film strength, meaning it provides a strong fluid film separating two surfaces sliding against each other.

Just looked at your Teslong pix. Scratches are low points not high points. Don't think low points scratch. You said you don't see the scratches till after sizing. I would think high points would make vertical scratches? Try a few cases with some motor oil you put on with your fingers. Don't understand the nasty tool marks in your photos. Maybe one of our gunsmiths can explain it.

Added later:
The marks on the cases are not scratches or low points. . They appear to be the copper oxide being rubbed off during the chatter in the die revealing the bright un-oxidized brass.