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300 Rum die help

Discussion in 'Ammunition & Reloading' started by xtratoy, Mar 10, 2012.

  1. xtratoy

    xtratoy Vancouver USA Active Member

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    I need to find someone with a 300 RUM that reloads and uses RCBS Full Length dies and RCBS shellholder so that I can size a couple pieces of brass. I have Hornady Custom Grade dies but they don't size the brass down enough to work in my chamber. Fired brass rechambers easily but once I run the brass into the dies it doesn't want to chamber easily. I am trying to determine if buying a new set of dies will fix the problem. Can any one meet me somewhere? I have a press mounted for portability and could meet you to resize a couple of my brass. I am in Vancouver WA.
     
  2. AMProducts

    AMProducts Maple Valley, WA Jerk, Ammo Manufacturer Silver Supporter

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    I unfortunately don't have a set of dies. However there are a few steps you can take to try to find out what's wrong.

    First you need to determine exactly why the case is not chambering afterwards. My suggestion would be to take a sharpie and color one of the cases that won't chamber, and then insert it into the gun (make sure it's not a live round) and note the areas where the color rubs off.

    My guess is the die is too tight, and as you reduce the radius of the cartridge case, it causes it to get longer, in which case the shoulder/base distance is changing which will have an adverse affect on your headspace. If you note rubbing on either the shoulder or base, this would be an indication of this. Also, you may want to measure the case neck and make sure the expander ball is not making it too large. If the brass is thicker than the expander is expecting this can also be a problem.

    Give that a shot, and let me know how it works.
     
  3. deadshot2

    deadshot2 NW Quadrant WA State Well-Known Member

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    You say the fired cases chamber OK? Try this. Take a sharpie and mark up the shoulder area of a fired case from the outside of the case to where it joins the neck. Back off the sizing die a turn or two. Run the case through the sizing die and then check the sharpie covered area. Adjust the die down 1/4 turn or so at a time until the die just starts to scuff off the sharpie ink. Then see if the case still chambers easily.

    Sizing is a pretty much straight forward operation but sometimes various dies have their quirks. Do you by chance have a "Neck Size" only die? If so, maybe it's "squashing" the shoulder if adjusted too far down and the bulge in the case wall is your issue. Take a case that doesn't chamber properly and "Plot" the diameter measurements at 1/4" intervals, starting at the base. Compare these measurements with a case that fits. All part of the "Investigation" necessary to find the issue.
     
  4. xtratoy

    xtratoy Vancouver USA Active Member

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    I have played with dies and " sharpied " the cases trying to determine what is happening. I just checked this morning and factory ammo that was difficult to chamber while the barrel was warm ( not hot ) chambers fine when the gun is totally cold. I can get the dies set where I have a minimal amount of force required to close the bolt but this is the first situation where I have had issues that have giving me these issues. I have been reloading for 30+ years.??????
     
  5. xtratoy

    xtratoy Vancouver USA Active Member

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    Factory brass measures .338 outside neck. resized brass unloaded measures .335 outside neck. Fired case which chambers easily measures .345. factory brass length is 2.845 and resized is 2.841 and fired empty is 2.840. I have been resizing brass to minimal tolerances by slowing adjusting to the particular gun I am reloading for years. I actually at first had to take several thousandths off the shellholder to even get the brass to size down enough to chamber. What I am not figuring out is why the Die is taking brass from the chamber that fireformed it and in the process of just trying to set the die for minimal sizing ( neck sizing with a Full Length die ) it is affecting the brass so it doesn't want to rechamber in that rifle. No telltale signs by checking with a sharpie. I would think that eventually by running the brass too far into the die that I would set the shoulder back and make the brass too small causing a headspace problem. If I just had a couple cases resized by a different brand of dies I could eliminate my first suspicion of the cause.
     
  6. deadshot2

    deadshot2 NW Quadrant WA State Well-Known Member

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    Have you contacted Hornady? It may be possible you have a mis-marked or improperly reamed die.
     
  7. xtratoy

    xtratoy Vancouver USA Active Member

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    No I haven't. I just thought that there would be someone in this area who also reloaded for 300 RUM that could hook me up and let me resize a couple of brass to see. I would then just go buy another set of dies. I have had real good luck with RCBS and LEE dies. I wish that Lee had a neck size collet die for this round.
     
  8. deadshot2

    deadshot2 NW Quadrant WA State Well-Known Member

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    Lee will build one for you for $60. Send them the money and two fired cases from your rifle. They'll send you a collet neck sizing die and a dead length bullet seater die. Lead time from 2-6 months.
     
  9. iusmc2002

    iusmc2002 Colville, WA Active Member

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    I tried to post about partial-resizing, also tried to PM it to you, but it wouldn't work. The gist of it was, run a lubed case into the FL sizer, until the shellholder touches the die and then turn the die out until you have about 1/16" between the shellholder and die. It said there would be a ring of grit/lubricant about 2/3 of the way down the neck, if you're doing it right. This SHOULD do what you mentioned, resizing the neck and not the critical shoulder dimensions. If you PM me your email, maybe I can send the whole write-up that way. I got it out of an RCBS reloading guide from 1972, but I can't imagine it would be irrelevant now. Wish I could help with the dies, but the RUM's are just too big for lil' ol me :cool:
     
  10. xtratoy

    xtratoy Vancouver USA Active Member

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    Or they could just make it a regularly cataloged item and sell it for half that price.
     
  11. xtratoy

    xtratoy Vancouver USA Active Member

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    I appreciate the offer and I just happen to have some reloading books describing the method you mention. That is how I adjust most of my dies to function in specific bolt action guns. I also reload for several semi-auto rifles and have never had a problem loading for them with standard dies. I don't own a single small base die simply because I have never ran into a situation that required one.
     
  12. iusmc2002

    iusmc2002 Colville, WA Active Member

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    Well damn, I was hoping to be the big breakthrough lol

    Again, good luck. Since you can't find a RUM set near you, I think I would contact Hornady directly, like deadshot said, their customer service is at least as good as Lee's in my experience
     
  13. deadshot2

    deadshot2 NW Quadrant WA State Well-Known Member

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    Just for fun and games, why not make a candle wax mold of the die and compare measurements with a cartridge drawing for the 300 RUM. Just remove the de-capping rod and plug appropriately. For a real accurate cast you could also use Cerrosafe, a metal that melts at about the same temp as M&M's.