Polishing steel sizing dies

[Wally]

Is anyone polishing their sizing dies? After using awhile steel sizing dies causes resized cartridge cases show small sleeks, even when the brass is thoughly cleaned. I suspect primer powder residue build up and becomes imbedded in the die...the material is abrasive and is probably powdered glass (silicon-dioxide). It cannot be removed with a tight fitting patch with a solvent. Rubbing the sized brass with fine steel wool will remove the sleeks; as will cleaning with SS pins. Was wondering what others use to polish theirs....

[Winger Ed.]

Sizing dies are about as hard as Chinese Algebra.
I've had to trash a couple over the years.
Now Days, I make sure the brass is super clean to prevent the damage to them.

[Wally]

Even clean brass--even really clean brass will eventualy show sleeks ..again from imbedded primer residue. Of course one can decap & clean the brass first--then resize. I chose not to do it that way..perhaps I should.

[Winger Ed.]

It's kind of a long way around, but when I set up for a cal. I process several hundred or a few thousand at a time.

I wash in soap & water, dry, tumble, then rinse the clean cases in gasoline.
It's kind of amazing what comes out with the 2nd rinse.
Then, after trimming, primer pocket cleaning, etc. they get rinsed again in gasoline.

Then get to loading and keep my hands & everything as clean as possible.
I got a new set of dies for .223 awhile back and have loaded about 2,500 rounds with them,
and so far, the cases look fine.

[lightman]

I have polished a few problem dies. I've used a bore mop with polish, a bore brush with bore solvent and a slotted cleaning jag with emory cloth with oil on it. I used a drill to spin these.

[country gent]

Streaks may be caused by uneven pressure around the case causing a uneven burnishing effect. Fired cases may not be truly round causing this. Look under magnification at the streaks and look for scratches in them.
Steel dies polish down with use and this shows more the finish in steel dies is meant to hold the sizing lube as it wears this smoother finish dosnt hold as much lube. The force required to size the case burnishes the brass surface.

I have polished / lapped sizing dies at times using diamond compound. They usually took a little more force and were more prone to sticking cases. The burnished effect was more predominant also. Even the coated dies ( chrome, TIN, and such) have the surface to help hold lube.

any grit should impregnate into the softer case material and scratch/polish the die steel. Thats how lapping works the softer material is loaded with the grit and cuts the harder materials. Thats why dies scratch the soft bras case holds the contaminates and carry it thru the die.

Polishing a die you need 600-800 grit a slow speed and high feed you want to duplicate that figure 8 pattern it holds the lube and distributes it. A mandrel for the grit paper and light touch. It takes good light and the right angle to see the pattern in the die.You dont want to bottom oput or pull out of the die as this will bell or damage the surfaces entering and at the end.

[Binky]

Following up on Lightman's post. Over the years, I have destroyed several sizing dies, both carbide and steel. A few years ago, I damaged a 308 sizer after not properly cleaning some range brass. I also used a bore mop. I crushed/ dissolved some jewelers Rouge in a little bore solvent and chucked up a saturated mob in my cordless drill. I then snugged up the die in a vice and polished the inside of the die. It worked! Infact it worked so well I tried on a couple of the carbide dies I had thought I destroyed. The carbide dies were, likewise, restored to usable.

[uscra112]

1200 grit crocus cloth on a balsa-wood arbor with just a little light oil. Medium hardness balsa is soft enough to conform to the shape of the die. I chuck the die in the lathe, rather than try to spin the arbor. If I had to do a bottleneck case die, I'd have to pre-trim the arbor to get it to enter the neck.

[BK7saum]

A lack of proper lubrication can also cause bits of brass to gall or "stick" to the inside of the steel sizing die. I have had it happen with new brass that I only wanted to neck size before loading. I did not lube the entire brass case before running it into the FL sizing die, but did lightly rub imperial wax on the case neck. The brass was undersize, so no risk of a stuck case, but it did lightly rub the inside of the die. After just a few cases, there were longitudinal scoring marks on the case body due to brass galling on the steel die.

[Bazoo]

I've polished steel dies and carbide with 1000 grit paper on a slotted cleaning rod tip turned in a drill, then with green scotchbrite pad, and finished with polishing compound on a mop.

I had one 30-30 die I polished a couple of times and it did not change the diameter of the sized brass a measurable amount (at least not measurable by me). It removed the problem and allowed me to get back into operation.

[Wally]

What a novel & clever idea!



1200 grit crocus cloth on a balsa-wood arbor with just a little light oil. Medium hardness balsa is soft enough to conform to the shape of the die. I chuck the die in the lathe, rather than try to spin the arbor. If I had to do a bottleneck case die, I'd have to pre-trim the arbor to get it to enter the neck.

[Wally]

Excellent method. Was the paper loose on the slotted rod, or was it tight?




I've polished steel dies and carbide with 1000 grit paper on a slotted cleaning rod tip turned in a drill, then with green scotchbrite pad, and finished with polishing compound on a mop.



I had one 30-30 die I polished a couple of times and it did not change the diameter of the sized brass a measurable amount (at least not measurable by me). It removed the problem and allowed me to get back into operation.

[Wally]

I never have had that happen--the sleeks on the cases I believe are from primer ash residue.



A lack of proper lubrication can also cause bits of brass to gall or "stick" to the inside of the steel sizing die. I have had it happen with new brass that I only wanted to neck size before loading. I did not lube the entire brass case before running it into the FL sizing die, but did lightly rub imperial wax on the case neck. The brass was undersize, so no risk of a stuck case, but it did lightly rub the inside of the die. After just a few cases, there were longitudinal scoring marks on the case body due to brass galling on the steel die.

[Bazoo]

I fold the sandpaper and put a strip of cloth between the halves. Then I wrap it around the slotted tip so that it's tight inside the die. The cloth gives it some cushion/give so that it will conform, but give snug pressure.

https://i.imgur.com/o5iQWtE.jpg

https://i.imgur.com/Mg5oh1M.jpg

[RichardB]

Flitz

[gloob]

Doesn't matter how finely polished a steel die is. Brass can still gall to it and then it will scar cases with vertical streaks. The easiest way to remove the tiny bits of galled brass is using fine abrasives. A bit of Scotchbrite adhesive sponge wrapped on a stick will do the job.

[Wally]

Well done--very clever!!!!!



I fold the sandpaper and put a strip of cloth between the halves. Then I wrap it around the slotted tip so that it's tight inside the die. The cloth gives it some cushion/give so that it will conform, but give snug pressure.

https://i.imgur.com/o5iQWtE.jpg

https://i.imgur.com/Mg5oh1M.jpg

[Bazoo]

Thanks. Forgot to mention, I lube with a bit of very light oil like RemOil or WD40 when using the sandpaper and the scotchbrite.

[Bmi48219]

1200 grit crocus cloth on a balsa-wood arbor with just a little light oil…..

Crocus cloth on a dowel spun with my cordless drill has always worked well for me. I deprime, clean w/SS pins and lube before sizing.
The times I’ve had dies start scratching my brass brass happened right after sizing 38 special nickel plated cases. Maybe these were just coincidences but I have plenty of 38 special brass brass so I don’t keep the nickel plated stuff anymore.

[Wally]

I use a lot of nickel plated brass in the .38 Spl/.357 Magnum. I found it best to clean it with walnut/iron oxide and place a 4" square of used dryer sheet soaked with Charcoal lighter fluid or paint thinner. This places a microscopic coating on the cleaned cases that remains and prevents the galling mentioned when sizing. The dryer sheet also removes some of the residue in the media prolonging the medias effectiveness.

[jetinteriorguy]

Even clean brass--even really clean brass will eventualy show sleeks ..again from imbedded primer residue. Of course one can decap & clean the brass first--then resize. I chose not to do it that way..perhaps I should.
So if I’m understanding your post correctly you are resizing your fired brass without at least cleaning it first? If so this is the beginning of the problem. Just deprime, then clean before sizing and don’t forget to keep the die clean and you’ll eliminate at least 90% of your problem. A little polishing of your die with Flitz on a soft Dremel wheel will take care of the other 10% of the problem.

[Moleman-]

When I have a die with some brass buildup or am making a new die I'll run a burgandy 3M pad on a split stick in/out of the die briefly. It only takes a few seconds to clean out brass streaks or leave a very fine crosshatch pattern on the die to help hold lube. I also always run the cases in a tumbler even if you run them a short enough time that they're not starting to polish up yet, it's already taken the grit off of the cases.

[Wally]

No Sir--I do clean my brass first before resizing.



So if I’m understanding your post correctly you are resizing your fired brass without at least cleaning it first? If so this is the beginning of the problem. Just deprime, then clean before sizing and don’t forget to keep the die clean and you’ll eliminate at least 90% of your problem. A little polishing of your die with Flitz on a soft Dremel wheel will take care of the other 10% of the problem.

[jetinteriorguy]

No Sir--I do clean my brass first before resizing.

Ah, upon rereading your posts I see where I misunderstood. Should have had more coffee I guess.