Die Leaving Scratches In Brass - Once Fired

Vyx313

Vyx313

Private
Minuteman
Feb 3, 2021
69
56
Wyoming
#1
I loaded up 200 rounds of 6.5CM and finally just got through most of it. I’m starting the process of starting the next batch after tumbling and annealing and I noticed that the die appears to be leaving scratches on the brass toward the case head end.

Most of the scratches are superficial but I can feel a slight ridge with my nail at a couple of places. Is this ok or do I need to do something about it? The die has been sitting in its box since I finished the first batch. I disassembled and wiped it out but I’m still seeing the same thing.

Pics left to right:
Leftover round from first batch
Case after annealing but before sizing
Sized case

3rd photo - closer look at sized case.
 

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#2
Vyx313 said:
I loaded up 200 rounds of 6.5CM and finally just got through most of it. I’m starting the process of starting the next batch after tumbling and annealing and I noticed that the die appears to be leaving scratches on the brass toward the case head end.

Most of the scratches are superficial but I can feel a slight ridge with my nail at a couple of places. Is this ok or do I need to do something about it? The die has been sitting in its box since I finished the first batch. I disassembled and wiped it out but I’m still seeing the same thing.

Pics left to right:
Leftover round from first batch
Case after annealing but before sizing
Sized case

3rd photo - closer look at sized case.
Click to expand...
If you have one, inspect the inside of your sizing die with a bore scope. You might find pieces of brass, like those you see from trimming) adhering to the inside of the die???
 
#3
I don’t have a bore scope but here’s what I can see. I’m assuming this is not supposed to be there right? What’s the best way to clean it out?
 

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#4
Vyx313 said:
I don’t have a bore scope but here’s what I can see. I’m assuming this is not supposed to be there right? What’s the best way to clean it out?
Click to expand...
Yup! That looks like the problem right there.

You can get a shotgun bore brush, wrap a large bore patch around it and soak it with something like IOSSO bore cleaner, then run it into and spin it around until all that is gone. Though it's not in focus, it looks like there there might be some dents in the edge of the die's mouth that's stripping brass off the cases and causing that brass to be pressed into the walls of the die??? Or, your lube just isn't doing the job well and this is the galling result.

I've used a polishing compound that to really smooth out the inside of my sizing dies and polishing my expander mandrels to help avoid any galling issues. Here's what I use:
 
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#9
I tried a mop and brush with some solvent and it took care of most of it. There is a little bit I couldn’t get off so I grabbed some of the polish Straighshooter1 recommended. Should be here tomorrrow to clean it up the last bit.

Thanks everyone for your input. It seems like I may not have been using enough lube. I sized all of the virgin brass using roughly the same amount of lube and didn’t have issues, it seems that that first firing expanded it a little more than I realized.
 
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#14
When I had this issue I got the brass out using Bore Tech Copper Remover which I had on the shelf and use for bore cleaning. Then...as said...a mop on a drill with some polishing compound.

I use Semichrome which I also had on the shelf (gads, tube of it must be 30 years old...I little goes a long way). I first came across this when in college and had a part time job at a joint that sold motorcycle parts and had injection presses to make helmet visors, face shields, and peel-aways. The mold maker...looked like one of the dwarfs in Lord of the Rings...used it to polish the inside of the molds to a perfect mirror finish. Good enough for him, good enough for me.


Flitz is probably very comparable but semichrome has been used in industry/professionals for over 50 years.

After that little experience, I make sure to lube the inside of my FL dies now....I use a little Imperial Sizing Die Lube (Redding) on a q-tip and lube the inside. Seems to have prevented the problem from recurring.

Cheers
 
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#15
Dealt with this a couple weeks ago... Long scratches from just above the base of the case up towards the shoulder area.

Looked in the die and could see whatever was causing the scratching had picked up brass from the cases.

Went out to my shop and chucked the die up in the 3 jaw chuck on my wood lathe. Chose an appropriate speed and used 1200 grit sandpaper first. Knocked down the rough parts and finished with a piece of scrap leather that I applied some polishing compound to... The compound is the same stuff I use to polish the edges of my leather cutting tools to mirror finish.

Worked well. After sizing subsequent cases I checked with a micrometer with vernier scale and saw no significant difference in case size.

I realize most folks may not have access to a lathe and metal polishing compound... But I had it and it worked.

I like the toothpaste suggestion too. Gonna store that one away in my head for future reference.

Mike
 
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