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Thread: Question du jour - expander die for 500 S&W

  1. #1
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    Default Question du jour - expander die for 500 S&W

    Hi,

    I've prepped the brass (primer pocket and flash hole uniforming, full-length resizing) and am ready to bell out the mouth of the case a bit for accepting the base of the bullet... 500 S&W that is, using a RCBS carbide 3-die set.

    Here's my question ...how to adjust the expander die? The Sierra manual and the flier in the die set are nearly equally vague. I only want the mouth to be expanded enough to let the base of the bullet to go 1/32" into the case and stay there when gently turned upside down.

    The expander die is a straight tube with the lock ring. The expander thing inside is a black gizmo that appears to be a 2-stage affair. Starting at the rounded end that points downward when installed, the expander has a particular diameter, then about 1/2" higher up, it expands to a larger diameter via a short 45-degree (or so) shoulder. I thought maybe this shoulder is what expands the mouth of the case, but the lower smaller diameter portion does not slip into the case (when tried by hand anyway, expander outside of the die.) The book just says "screw the die into the press until it just touches the ram, then insert a case and run it all the way up ...adjust the expander up or down to suit." Not much help there and why do they pretend the factory installation would be anywhere close?

    So can someone explain how the expander thing is supposed to work (flared by the end or flared by that upper shoulder)? If it's flared by the upper shoulder as I think, then will the lower portion of the expander make the case too big or is it designed, not that the case is resized, to restore the inside of the case to factory-spec to fit bullets ...assuming that due to brass thickness differences, the full-length resizing will likely leave the inside diameter too small.

    Here's what I think I should do: back out the expander enough to know it taint gonna bell that mouth properly, then keep running the case in and out while I slowly adjust it inward until I get the neck expansion that I want. I'm going to assume the lower, narrower, portion of the expander is SUPPOSED to be forced into the case in order to set the inside diameter right. No? Yes? BTW, I'm just working on my dummy round that'll be used for future bullet seater adjustments (make them quicker.) If I waste a case at this point, I'll get over it.

    Thanks,
    Brian

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    Ahhhh! Yes, mostly. You ask good questions. The expander lower portion should be forced into the case and the upper step should be forced into the case to allow the bullet to sit freely in the case to, oh, I don't know I guess the 1/32" or 1/16" of an inch is about right. I want bullets to sit in the cases when I seat them with finger pressure and when I invert the case, the bullets stay put. This makes handling and seating them easier and you can see that the bullet is straight in the case before going into the seater, that is a big deal. The dimensions of that expander, if you have a mike should be about .0015" to .0020" smaller than the bullet spec diameter and that is .500", for the S&W, (.4980" to .4985") and the upper portion of the step expander plug should be about .002" to .003" larger. Now I realize it is tapered with an angular shoulder but there is a full diameter above the shoulder and that should be the larger size. Experiment with that adjustment until the bullet will sit straight up in the case during handling. The bullet will actualy "snap" into the larger expanded portion.

    The Redding and RCBS expanders are different in that the step up diameter is more shape on the Redding and it seems to make this easier, even though it would appear to stress the brass more between loadings of sizeing, expanding, crimping, firing, sizing, expanding, .....This works the brass a lot at the mouth and will cause splits quite often. The RCBS expander will need to be forced into the case a bit farther to compensate for the length of that shallow shoulder because we need to get to the full +.002" diameter to allow the bullet into the case by finger pressure. Both work well and I've had no problem with either. With the 454 RCBS expander I did need to sand the expander smooth and remove about .001" of diameter to make a tighter fit and keep the bullets from jumping crimp. The 500 S&W has the compensator on the muzzle which reduces recoil a lot and bullet jump is not generally an issue. I usually polish off that oxide coating anyway with 600 grit to smooth things up and a few ten thousands smaller doesn't hurt. Ain't this fun?
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    And your answers are always good! I'll measure the expander tonight, just for information's sake and maybe post a picture. If I recall, the upper portion looks like a lot more than a couple of thousandths larger in diameter ...More later.

    Brian

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    Quote Originally Posted by tananaBrian View Post
    And your answers are always good! I'll measure the expander tonight, just for information's sake and maybe post a picture. If I recall, the upper portion looks like a lot more than a couple of thousandths larger in diameter ...More later.

    Brian
    You're probably right now that I think about it. The RCBS expander plugs have a rather long tapered shoulder and I think you are supposed to only bell the mouth to accept the bullet. The Reddings are a steep step up and actually make two different diameters of the case. I like the Reddings because I can set the bullet it in it and it stays put, but the Redding dimensionsare more critical. The RCBS will bell the case mouth to probably .020" bigger than bullet diameter if you go too far. So...they are used differently...but both do their job.

    Just an added note. I measured my Redding expander and it measured .497" and .501" just with the dial caliper accuracy so the second step is just .001" over bullet dia then the third step, I guess, is just a sloping shoulder to bell the case slightly.
    Last edited by Murphy; 01-16-2008 at 19:50. Reason: More vital info....
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    Ok. Got the expander die all set up and my first 20 rounds ready. I didn't measure the 2 diameters of the expander itself but in just looking at it, I think it must be 1/32" larger (or even more) than the lower section. It's quite obvious that you'll never be forcing THAT into the case. The lower section slips into the case snuggly but not tight ...it goes in just right I'd say ...any easier and I'd say 'too easy'.

    I just screwed the die in until it barely met the ram, then adjusted the expander downward until you could feel a slight resistance as it belled the mouth of the case. Too much. The bullet sat in the end over 1/16" deep. Had to use the crimping die to straighten out that bell so I could try again. This time I progressed more slowly and locked things in place when I got the 1/32" seating (and the bullet stayed in.) Measured the length of the cases and they were all very very close, so I ran them all through the expander (randomly checking bullet fit on about 1/4 of them) and called it good for tonight. I really can't go any further until my taper crimp die (for those electroplated bullets that I have) gets here... should be here tomorrow through Saturday I think. BTW, no worries on overworking my set-up case. It'll be my dummy round for setting the bullet seater in the future ...no primer, no powder, but has bullet and crimp. I'd really like to try my first reloads this weekend ...

    Thanks,
    Brian

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