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Thread: modifying a Lyman sizing die?

  1. #1
    Boolit Buddy am44mag's Avatar
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    modifying a Lyman sizing die?

    I'm trying to figure out the best way to get the sizing die I need for a gun I'm getting soon. I don't have the gun in hand yet, but it SHOULD have a bore around 0.366-0.368". Lyman makes a 0.366" die, but that is cutting it very close. I know you can enlarge a LEE die (none are really close enough in size for this rifle), but can you enlarge a Lyman die by 0.001-0.003 or is that going to cause problems?
    ______________________________________________
    Aaron

  2. #2
    Boolit Master Maven's Avatar
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    Aaron, It can be done, but it is a slow, trial & error (hopefully not the latter!) process. Btw, I just did one two weeks ago using the same method as in enlarging a Lee sizing die (use this site's search function for how to's if you need them) and it worked quite well.

  3. #3
    Boolit Buddy
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    Totally doable. I just opened up what was supposed to be a .278 die that was actually .2765. It opened up to 279, no problem.

  4. #4
    Boolit Master

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    It can be done in several ways, some are pretty slow others faster but more chance of messing up. these are hardened dies so it takes some work, the lube holes can also cause issues with cutting them. Here are 3 ways

    1) polishing, this can be a easy way to do this project.
    a wood or aluminum dowel (5/16" works for the size you want of .366) 6" long. Split on center line 4" up from end. This is the mandrel
    fine wet dry sanding paper in 320-800grits cut and fit a piece 4" wide at a length that makes a snug fit in the die when wrapped around the die.
    Start with the 320 and work slow. a low speed rpm and high feed not coming off the paper. Coming off the paper causes belling on the edges and also may require rewrapping paper every time. Make a few passes back and forth, you want the polish lines to cross over looking like figure 8s in the die. A little oil (clp kroil or other light oil) on the paper keeps it cutting clean.
    work thru the grits as you go. measuring often for size.
    For final finish a piece of flannel and flitz simichrome or toothpaste gives a very fine polish.
    Measuring can be done several ways. A lead bullet can be pushed thru and measured with mikes. this works well and is easy to do. pin gages can be used again quick and easy. small hole gages and mikes here the lube holes may affect the measurement and your working with 2 feels one setting the pin gage and then measuring. Last and least accurate is the inside jaws on calipers.

    2) Honing, this requires a actual machine. It is very accurate and controllable. Mount appropriate hone in spindle and adjust dress the hone and hone out checking size often this often leaves a fine enough finish that polishing isn't required.

    3) Boring in lathe or mill. this is a tedious set up for the amount being removed and carbide tooling is needed. The lube holes will set up vibration patterns and may also chip tooling due to the interrupted cuts. Requires setting up in a 4 jaw chuck and indicating into dead 0. This method can also leave burrs on the lube holes that are hard to remove. This is the fastest way to do this but is also easiest to go over size with.

    4) Lapp. is to coat bullets with lapping compound and push thru die. you can push 1 slug thru 4 times rotating 45* each time. this method requires a few slugs lapping compounds and a small press. It does alighn polish lines down the bore not around it. It takes some time to do and if not square and tru will produce oval holes.

    Cast a batch of bullets mark bases with a scribe. impregnate a bullet with compound rolling between 2 flat steel plates. push thru die 4 times rotating 45* each pass thie rotation will help to keep it round and true. Run a couple 3 bullets thru as above measure work thru finer grits until out to size.

  5. #5
    Boolit Master

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    lee will custom make sizers.

  6. #6
    Boolit Master 243winxb's Avatar
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    Wood dowel and emery paper works.

    Different alloys will produce different finished bullet diameters. Softer=smaller.

    My Lyman "357" die was producing a finished bullet diameter of .3575" for years, using range scrap. Then was give 80# of near pure lead . Bullets became smaller at .3571"

  7. #7
    Boolit Buddy 15meter's Avatar
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    Sounds like a 9.3 of some flavor. I had lathesmith (vendor here) make me one for a 9.3x74r for what I thought was a reasonable price.

  8. #8
    Boolit Buddy
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    I opened up a lee .358 to .368 for my 9.3's using the methods described here. Works fine for my needs.

  9. #9
    Boolit Buddy JMax's Avatar
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    I also recommend Lathesmith as he has made several dies and plugs for me, excellent service and price.

  10. #10
    Boolit Buddy
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    I have done one RCBS and one Lyman so far. The Lyman I did with the polish method as it was .431" and I needed it .432". The push pin I left alone:



    This is the body after the slight polish job:



    For the RCBS, however, I opened up an RCBS .458" die to .460", but the polish method was not fast enough since the die was hardened. I put it on my lathe, and took several light cuts until I got close, then used the polish method to finish up. Man, even with the lathe the hardened die was tough!.
    Here is the original pin at .457":



    Once I got to .460", then I sanded and polished it down a bit:



    Original .457" on left, new 0.459" on right:



    Here is the new custom steel pin I made at .459":



    And the die, which ended up with a 0.0005" difference:





    These 45-70, 405gr hard cast were already sized to .460" using a Lee push through sizer but not lubed. Here is the result in the new opened die:






    Will
    Last edited by wquiles; 06-09-2018 at 12:09 PM.

  11. #11
    Boolit Buddy am44mag's Avatar
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    Yep, it's for a 9.3x57 Mauser. I've done the ol dowel and sandpaper trick with a LEE dies before with good results. The Lyman is close enough that I can't justify a custom job. Maybe I'll get lucky and have a slightly undersized bore, lol. Wouldn't have to do a thing then.

    If not, I might try rigging something up on my wood lathe to make the job easier. The main worry I had was if I was going to have serious leaking issues if I enlarged the die. I didn't know if that steel pin had to be super tight or if it could have a bit of play in it.

    Thanks fellas for the advise.
    ______________________________________________
    Aaron

  12. #12
    Boolit Master


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    Your push pin might work in your .001 to .002 oversized die. Will depend on the consistency of your lube and the pressure you apply it.

  13. #13
    Boolit Master 243winxb's Avatar
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    The Lyman push pin would be a problem if honing out more then .002" As said above.

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