Question regarding the diameter of a STAR sizer.

[FN in MT]

I have a .430" STAR sizing die that will accept a .429" pin gauge and seems to give me a .4285" or at best a .429" slug. A .430" pin gauge will not go in. Measured my sized slugs with both a 0-1" micrometer and a pair of quality dial calipers.

I assume the die should be .430" if that's what it's marked?

Wondering if I could have it opened up a .001" so I can get the .430" slugs I desire.

Any idea if Lathesmith would do the work?

[VHoward]

Yes, Lathesmith will open them up for you. How soon after sizing are you measuring? Some alloys take longer to rebound to their final size. Take the same slug you measuered and measure again in a week or so.

[FN in MT]

The slugs I measured were sized/lubed last Winter or this Spring.

I'll contact Lathesmith...thanks.

[hermans]

I had the same problem with my first Star die, was stamped .453, but the boolits measured .451. Contacted them, and they said they made a mistake.
I agree in contacting Lathesmith, he guided me to open up my die in no time by sizing some boolits covered in valve grinding paste.
This does takes a bit of time, but it works!

[Landshark9025]

Or you could take some 600grit emery cloth, wrap it around a brass rod and run it up and down your thigh for a bit. Trial and error and you can't go back if you take too much out. But it works.

[dragonrider]

What Landshark said is the best method for removing small amounts of material from a die. HOWEVER clean and check the size often so that you can creep up on the desired diameter.

[FN in MT]

Going to try the dowel and 600 grit method......Thanks for the suggestions.

[frank505]

My experience with magma size dies is they get close. Open it up yourself.

[Landshark9025]

Another thing you can try, is after you feel like you are "close", take an already sized boolit or several, coat it in Flitz, and pass that through. This will give a final polish to the inside of the die.

WARNING WARNING WARNING

As soon as you feel a "squeaky resistance" or any one of them feels more stubborn than the last, or if you have run three of them through, STOP, clean out the die and try it. You can get a boolit stuck with Flitz and it goes from "that felt a little stiff and kind of like dragging a wet finger down a window pane" to "****, this isn't good" real fast. But if you don't screw up, you end up with a highly polished die.

[wv109323]

I just went through this exercise with a Star sizing die. It took a lot of time to open up my .358 marked die. It sized at .3577 and I wanted .358+ because my bore is .3572.
I started with 400 grit and could not open it up with a drill press and flap wheel. I probably spend 10 minutes polishing and could not measure any enlargement.
I then went to 100 grit and spent 5-7 minutes polishing to open it up from .3577 to .3581. I then cleaned it up with the 400 grit.
I ran bullets through the die at least 20 times at different intervals to measure my progress or lack thereof.
My die is an original Star some 20+ years old. YMMV
I surprised me the amount of time it took to open it up .0004".

[FN in MT]

I took some 400 grit.....attached it to a .4" aluminum rod. Chucked rod in drill press and fairly quickly took it down to a true .430". I did go from 400 to 600 for a final polish.
My die is an old STAR die.

FN in MT