Rifle Sizing Dies: ULTRA Polish or cross-hatching? What's best?

Messing with the inside of a rifle die is something I had never even contemplated. If I scratch one with a missed piece of grit I toss it in the junk box and replace. For the rifles I am realy concerned about I have my dies custom cut by the same guy that cuts the chamber in the barrel. That is where you find accuracy. Matching the inside of the die to the rifle chamber. Your mileage may vary.

I've polished most of my RCBS sizing dies. The sizing is noticeably smoother and requires less lube. The difference was instantly noticeable. Piece of cheap cleaning rod chucked in drill with paper towel wrapped on closed loop jag. Add flitz and polish LIGHTLY.

I've polished several dies. Most weren't very bad, I just like them really smooth for easier sizing - but one Lee rifle die was rough enough that my brass went in shiny and came out dull. They said it wouldn't be a problem but I wasn't happy with that.

I almost always polish the expander buttons.

Must be pretty cold there...

Mirror finish is preferred. Any roughness will capture brass deposits and end up scratching or scuffing your brass finish. It'd take a lot of sanding-polishing to remove even a few tenths of a thousandth inch. You wouldn't want to start with a rough grit and keep working down to fine grits as you could take off too much. Starting with a fine polishing paper is what I use to clean up and restore the finish should one of my dies pick up a piece of grit or an area that is scuffing the case from brass deposits inside the die. Some rifle bore cleaners to clean dirty dies but very fine polishing paper by hand or in a drill works great and several polishings won't remove enough internal diameter to even notice it. The die internal surface is harder than soft mild steel.

Most resizing dies I've used size down more than is necessary, thus the expander plug that brings the neck back out to the needed diameter, so I agree you probably don't have to be too concerned about taking too much off if your careful.

But, the body sizing part of the die could be an area where you might encounter a possible issue due to inadequate sizing of the body of the brass if you removed .001", I would think? I would be concerned that the brass might not have enough tollerance in this region, thus possibly causing the brass to bind when chambering. Most of my brass is some where between .001" - .0015" expanded after being fired, from about half way down, between the shoulder and the web region. And the upper half is usually an even tighter tollerance in rifles I load for. Of course there is some brass spring back that occures, so I'm fairly certain those measurements aren't completely consistent with the chamber tollerances. But it is also necessary to have the necessary degree of brass to chamber tollerance to account for spring back, so as to not create a problem with brass fracturing due to it over expanding, as I would think this could occure as a result when fired if too much material is removed.

I'm by no means an expert in this area and I'm sure there are others here who are and could better advise you in this respect.

But I do polish my dies if I notice any scratching or marks on the brass surface after resizing. But I don't use sand paper or car polish, I use an extremely fine honing compound initially, and then I finish with some of my super fine lapping compound to give them a mirror finish.

GS

"...on the lees I have), the finish is not a mirror gloss but more of a crosshatched rough finish."

777, years ago I decided to clean out the tiny bits of galled brass in three of my FL sizers because it was scratching my cases more than I was willing to accept. I lapped the insides much as you did, checking from time to time to see when the galling was cleared. Of course there was a soft matt finish left inside at that point. I resized several cases before polishing the die wall of the first to a mirror shine and sized again; somewhat to my surprise there was a noticeable increase in the required effort and the amount of lube I needed. The other two gave the same result as the first. (All else being the same, different lubes and how well it's applied does affect sizing effort.) I then restored the matt finish with a green 3M pot scrubber pad wound tightly on the wooden dowel lap and did the same to the rest of my dies; I've not had a recurrance of the galling. My assumption is as you suggest, just as a auto engine cylinder wall needs a cross hatched matt finish to hold lube, so does a sizing die.

It's as unlikely we can 'scratch' a file with bit of grit as we can scratch a sizer with the same grit; virutally zero. Files, size dies (and some seaters) are case hardened, any grit is going to be smashed into the soft brass, not into the die wall; we normally can't scratch a sizer die even with a file or hack saw, it takes a carbide cutting tool or a grinder to cut into that very hard surface! What produces case scratches coming out of a sizer is usually bits of brass that have galled onto the die as firmly as if it's welded due to insufficent case lube. Clean your dies, lay on a bit more case lube than you normally use and the die 'scratches' probably won't reccur.

The only time that I have polished a die was when they picked up enough brass or other junk to scratch my cases. A bore mop in a drill and a little polish did the job. I do clean my dies with bore cleaner, and I always clean a new set of dies before using them. Some have been very dirty while others have not.And yes, the 3M pad and 4/0 steel wool is a reloaders friend! Lightman

Rifle Sizing Dies: ULTRA Polish or cross-hatching? What's best?

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With sizing dies if you look at the interior (at least on the lees I have), the finish is not a mirror gloss but more of a crosshatched rough finish. I'd expect this is because they don't want to spend the time required going through the grits to polish the surfaces”

and then,

“What have you found?”

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I did not discover the '”leaver policy”, but, I am a fan of the leaver policy, when I receive a new set of dies I leaver the way I received-er, when cleaning them I use a towel on a dowel, I do not use brake degreaser ‘BECAUSE of the cross hatch honing"? (think about it, how difficult is it to cut a cross hatch pattern on an inside taper?). Lube has weight and takes up space, lube will fill the cross hatch? machineed pattern, filling the scratches? with lube makes the cases ride up inside the die smoothly.

A few years ago it was decided the chamber did not need to be smooth, the thinking popular at the time decided the chamber needed “the cross hatch pattern” for ‘GRIP’ to prevent the case from sliding??, not me! I want all the grip I can get, there is nothing that has more grip than 100% contact, meaning? A smooth, shiny, free of scratches and absence of oil and lube chamber is as good as it gets.

Knowing lube is a fluid, that flows and can not be compressed will fill the scratches in the die and aid in sizing and case removal I apply the leaver policy, I leaver the way I founder.

Then there is that problem with lube and no place to go, I avoid lubing the neck and shoulder of a rifle type case to avoid dents in the shoulder, ( back to fluid/lube is a fluid, it flows and can not be compressed) when a case is sized after having been fired the case body diameter is reduced, reducing the diameter of the case body causes the case to increase in length, same for the neck, when the case neck is sized down the neck gets longer. The absence of lube on the shoulder and neck make it difficult for the case to slide past the neck and shoulder part of the die, again, fluid flows, I do not assume the lube on the case does not flow even though there does not seem to be enough room for the lube between the die and case.

Then there is always the question about stretch and or flow, or is the question, "Is it it stretch and flow?

“What have you found?”

I have never found skid marks on my cases, I am the only one that has marked/scribed lines on a case before and again after firing. and again “What have you found?” I have never found the line where bumping ends and forming begins.

F. Guffey