10mm boolit Question on sizing

[Side by Side]

I have an RCBS 200gr 10mm mold, listed at .401, I slugged my barrel, it is at .401, lube/size die can only be purchased at .401. Should I shoot them as cast(haven't cast any so at this time as cast size is unknown) I'm thinking I should be shooting .403. can't purchase a die at .403?

[Love Life]

Purchase a Lee push through and hone it out. I use a wood dowel and varying grits of sandpaper and it takes me about 20 minutes. I finish it with 1500 gr and polish in a vertical motion.

[petroid]

Cast some up and see how they drop. They may drop .402 or even bigger. If they are consistent and round and not more than one or two thou over your slug, try to load some. Love Life is right, you can always hone out a lee sizer. Mine sizes to .4015 with my alloy which is perfect for my .4005 grooved XD. Make sure you water drop your boolits and your dies adequately expand the case. 10mm and 40 are high pressure rounds and brass will swage the boolit down if not expanded properly and the alloy hard enough.

[fredj338]

If your slugging is accurate, I would want a 0.402" You can order a Lee die that size or have any other die polished out to that. Your mold may cast that size or you could beagle it to get it there & shoot as cast size.

[a.squibload]

Also consider that the finished cartridge might not chamber reliably,
that's where I'm at right now with oversize 40s. Have to push the slide
to battery with my thumb on a few of 'em. Can't be nose shape as they're
almost in there, must be diameter, I guess. Think I'll start over and do the Lee sizer mod.

[shooter93]

Rick..aka Buckshot here can make you a sizing die in any diameter you want. I never slugged my 1911 10 mm but it does shoot .401 commercial bullets quite well. I had Rick make me a couple sizers for the 10 mm so when I get a mold I'll mess with it some but it does shoot 401's well.

[DLCTEX]

You can also hone out an RCBD/Lyman die same as a Lee die. If you take it more than .002 it may leak past the pusher (I part).

[Whitespider]

Also consider that the finished cartridge might not chamber reliably,
that's where I'm at right now with oversize 40s. Have to push the slide
to battery with my thumb...

I had the same problem with .4025 boolits in my .40 (some headstamps worse than others).
I used the wooden dowel, fine grit emery paper, and oil to polish out the chamber about .001... problem solved, although I do still haft'a avoid a couple of headstamps with thicker brass.
*
*

[a.squibload]

Hmm, hadn't thought of that, a little scarier than polishing a die but could make that chamber
a little more forgiving on different types of ammo. Need to research whether the barrel/chamber is
surface-hardened inside or solid, could that be an issue with polishing it out? It's really shiny in there.
I forget that all brass is not the same.

[Love Life]

I use that exact same mould and it casts to .4025X.403 using my hodgepodge of alloy. You want to work in steps here.

Cast first and get the diameter. Then go from there.

[Whitespider]

The barrel, or chamber, won't be surface hardened... actually barrel steel is usually quite soft, relatively speaking.
I slugged the chamber first and started with 600 grit... make the paper tight enough so you can feel it come up against the shoulder.
I finished it progressively using 800, 1000, 1200 and finally 1500 grit wet/dry paper and a bit of light oil (the 1500 was overkill).

Another issue I had with .4025 SWC's was the boolit's shoulder catching, or hanging-up on the chamber shoulder... which would stop the slide just short of going into full battery. I had the boolit seated out like that to solve feeding issues. I ended up seating them just a touch deeper and that problem also went away.
*

[MtGun44]

Are you measuring with a micrometer or caliper? If caliper, you need to upgrade to a micrometer before you do any
of this, since your measurements are not really accurate enough to be sure of any of this. You can get a real
decent mic from EncoUSA online - about $35 for a nice Fowler - get one that reads to .0001 so you can actually
trust it to better than .001. Calipers are good for +/- 0.001, so your measurement of .401 could be actually .400 or .402.

Bill

[steve4102]

I have an RCBS 200gr 10mm mold, listed at .401, I slugged my barrel, it is at .401, lube/size die can only be purchased at .401. Should I shoot them as cast(haven't cast any so at this time as cast size is unknown) I'm thinking I should be shooting .403. can't purchase a die at .403?
Sure ya can.

here is one source and there are others.

http://www.accuratemolds.com/moldBlock.php

[khmer6]

What 10mm are you shooting that's slugging large?