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ph4570
04-29-2009, 09:24 AM
Good Morning,

Among others cast boolits I cast for my 10mm auto SW 1006. I have been using an ancient Lyman sizer and a .401 Lyman die. My 6 hole Lee mold drops nice boolits with a diameter of .4025 and very round. My alloy hardness runs about BHN 15. Boolits sized with the Lyman .401 die come out exactly .401 and very round. Sizing from .4025 to .401 is effortless for the Lyman. These boolits are accurate in my SW and I have never had any leading.

A couple of days ago I aquired a new Magma/Star sizer and a Magma die marked .401. The sized boolits are .3995. This is not what I wish from a .401 die! Also, sizing from the cast diameter of .4025 seems to be straining the Magma. I did the trick of running a lubed boolit through about every 15 boolits and that does help but I am concerned about straining the Magma sizer and possible breakage. So, my questions are:

1) Has anyone else had an issue with Magma dies sizing too small?
2) What would be a good way to open up the die a bit?
3) Is sizing from .4025 to .3995 with BHN 15 too much to ask of the Magma/Star sizer? Perhaps it will be happier with a true .401 die.

BTW, a boolit came with the sizer that was presumably run through the .401 die. It measures .3995 just as the ones I sized. I have not yet queried Magma about the die issue as I just ran boolits through it for the 1st time last evening. I will call Magma later today.

Thanks in advance for your comments.

ddeaton
04-29-2009, 10:13 AM
Get in touch with Lathesmith on the forum here. He makes great dies for the Star sizer. I do not have enough experience to give you good feedback other than the die was made undersize. If it is hardened it would be hard to open up to specs. Others will chime in here that know more than me, but I will say all the dies I have from Lathesmith have been on the money.

ph4570
04-29-2009, 10:21 AM
I ordered three dies from Lathesmith yesterday. I probably should have gotten the .401 from him as well.

GabbyM
04-29-2009, 10:47 AM
You can coat a couple of bullets with 600 grit lapping compound then run them through a couple dozen times. Then clean up and check diameter. Dies will open right up. I use a little oil too so the lapping bullets don't get stuck. Use your finger or a Q tip to oil the die before you start. I've used 220 grit but it scratches the dies and by the time you lap out the scratches with fine grit you may as well have just used the fine. You can also polish with a mandrel holding emery cloth spun in a drill. Use WD-40 or other fluids. If you don't like to play machinist Magma will open the die up for you. But you'll be out shipping. Most of their dies are small. They leave to much for spring back IMO. They must use rubberized lead. Also if your trying to read .0005” on a caliper you're stretching the limit of that tool. You'll get a couple of tenths depending on how hot the sizer is heated to. From room temp to the 130 degree lubes. Before you get to adamant on the size you need to use a check gage to verify your caliper or micrometer.

Also if the bullets are sizing hard a good polish with 1200 grit compound, or maybe you have some JB bore paste , will shine the die up and save your elbow.

Hope I've not just confused you.

ph4570
04-29-2009, 11:05 AM
Thanks Gabby. No confusion with your post -- good tips. I brought a boolit to work this morning and had my friend in the model shop check size. He used 2 different digital calipers and and a micrometer. He got the same results as I did with my digital Mitutoyo caliper. His gauges are regularly checked for accuracy.

I have several grits of lapping compound and an Atlas lathe. I believe I will attack the Magma die using one method or the other.

Springfield
04-29-2009, 12:03 PM
I would just call Magma and have them exchange your die. Mine have always been spot on but anyone can make a mistake. If they say the .401 is fine then order a.403. All lead doesn't size the same, the harder bullets tend to have more springback then pure lead.

Firebricker
04-29-2009, 12:40 PM
I'd send it back to Magma to open it up all the size dies I bought with my Star are right on. But I highly recomend lathesmith I'll the ones I've bought since have been from him super quality fast turn around time. BTW flat out nice guy to do business with. FB

cajun shooter
04-29-2009, 03:03 PM
ph4570, I had a 454 Magma die that was on the small side. I sent it to Lathesmith to correct. Might want to do that instead of messing up die. Later David

lathesmith
04-29-2009, 04:07 PM
ph4570, and others,
As usual, the advice I see here is spot-on. There is plenty of info here on opening up a die, no matter what brand, and I think it's right on, so I won't repeat any of that.
I will say this: The way that I size my dies, and so does Star, Lyman, RCBS, and any others that I have checked, is this way: Say you want a .454 die. A 453 pin gauge is "go", and a .454 gauge is "no go". In other words, a .454 die is actually .453; this is to allow for "springback"of varying lead alloys. Since there are dozens of casting alloys, guaranteeing an exact sized bullet diameter is not gonna happen, at least at prices most folks can afford. Your best bet, if you really, really need a size within a few ten-thousanths, is to order a die .001 smaller, and then open it up like some of the guys suggest above. That way, you get a custom-sized die, just that way you want it, without the super-premium price. Remember, to properly make these Star dies, I have to hold two surfaces to within +-.0005 or so; if tolerances have to be held closer than this, the manufacturing time goes way up, and then so does the price.

I say all this to help everyone understand a little better how these dies are made, and this will hopefully help you to get as close as possible to the size you want. ph, I'm guessing that if that Magma .401 die is .001 too small for you, then one of my .402 dies should be very close to what you want. Note I say "should be", this is still a guessing game, and it is also not unusual for measuring tools to differ .001 or so. So many variables....

BTW David, I will get your die finished and mailed to you on Thursday, I apologize for being a little slow. Things have been very busy around here lately, and then a few unexpected and un-delayable "home repair" jobs have popped up, which has really kept me on my toes!
lathesmith

runfiverun
04-29-2009, 08:20 PM
it depends also on the poured diameter of your boolit.and the alloy.
i have a 45 that pours at 4545 i size to 452 is comes back to 453.
just what i wanted.
others i have pour to 453 i size to 452 they come back to about 4525. maybe.

ph4570
04-29-2009, 09:58 PM
I opened up the die a bit at a time. I now get the .401 boolits my S&W 1006 craves. The final polish was with crocus paper and simichrome paste. Thank you all for the helpful comments.