TALK TO ME ABOUT POLISHING A SIZING DIE

[StanCT]

Dear Forum members,

Nothing clear comes up from a forum search, and it is something that I have seen mentioned here over the years.

How does one go about polishing a sizing die that is damaged?

I have a sizing die that scratches / scrapes the neck as shown below:



How does one go about 'polishing' this out of the die's internal finish effectively, or is it a waste of time, and is it just easier to replace it?

I understand that 'polishing' requires some kind tool like a dremel-type or drill high speed rotational device with some kind of polishing paste, but can anybody share practical tips and experience?

[driepootx]

That almost looks like the remnants of a case neck that are still stuck in the die. Try and get a look in there with a bore scope. You did not perhaps resize a nickel case?

[StanCT]

I don't know the history of the die, because it was a 2nd hand purchase, but this is the first case that I ran through.

I've had a good look inside and there is nothing stuck in there.

Could sand or dirt in the die have produced this?

Regardless of how it came to be, my focus now is on establishing whether it is feasible to attempt to polish the defect out - and how.

[Ds J]

It looks like the die is tight and scratched.

I read somewhere about soft sanding paper around a dowel stick, or abrasive compound on a piece of cloth.

[driepootx]

Those look like serious scratches. You might find if you polish all that out then the case necks will not be reduced enough.

The way the neck in the picture has been scraped down suggest that the neck portion of the die is way too small. A question - what make and calibre of die?

[414gates]

Wrap a correct size cleaning jag in a patch, coat the patch in burnishing compound, and put the jag on the end of cordless drill.

Rotate the jag inside the neck portion of the die for a minute. You may need to do it a couple of times.

You will remove any material deposited during the sizing operation, and also polish the die steel.

There is no way to remove any steel from the die using this method.

[StanCT]

This is a Lee 300 Blackout die.

Thanks, 414G - that's exactly what i did, and ... voila!

First a bit of polishing paste, then finished it off with some Brasso.

Probably no more than a few min of actual polishing work, but having to let the die cool down a bit from time to time.





All input much appreciated - feeling chuffed!

[Gleock]

Are you lubing?
The inside of that case mouth also looks scratched.

[StanCT]

Yes - there appears to have been damage to the inside sizing ball as well, which I have also managed to polish out.

[Ds J]

Is there a particular burnishing compound one should either use, or stay clear from?