Rounds Not Chambering?

Discussion in 'Reloading' started by Elk Chaser, Sep 17, 2010.

  1. Elk Chaser

    Elk Chaser Well-Known Member

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    I've just recently begun reloading for my 300 RUM but I've run into a problem with my finished rounds not chambering. My first reloads were from once fired factory Nosler brass that I resized with my RCBS F/L die and seated to the lands for load development. Now that they are twice fired and resized they are not chambering for me. The cases are below the 2.866" my gun smith gave me for a trim length and the bullets are approximately .010" off the lands per my Hornady OAL gauge. I'd like to get out this weekend and continue working up a load but this issue has me stumped. Does anyone have a suggestion as to what the problem may be?
     
  2. Broz

    Broz Well-Known Member

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    This is usually due the the depth of one of the dies being adjusted either to low or not low enough.

    If the sizer is not low enough it will not move the shoulder back enough.

    If either the sizer ot the seater die is to low the case can bottom out and cause it to deform the case. This condition is usually found with a seater die though. Try adjusting the seater dies up a bit first. If the problem continues, lower the sizing die.

    Jeff
     

  3. Elk Chaser

    Elk Chaser Well-Known Member

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    Thanks Broz,

    Another thing that maybe I should've mentioned is that all of my sized brass chambered smoothly prior to seating the bullets. Both my sizing and seating die are set up the same as I bottom them out against the shell holder and then back them off 1/2 turn. Do I need to dis-assemble these rounds and try lowering my sizing die?
     
  4. Broz

    Broz Well-Known Member

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    If they fit before you seated the bullets and not after then the problem is most likely the seating die is contacting the case and deforming it slightly. The sizing die is probably ok.

    Yes, you need to pull the bullets, dump th powder and resize the brass.

    Here is a tip to set the seating die depth so you will never have this problem again.

    1: put the seating die in the press but leave it up.

    2: put a sized case in the shell holder and extend the ram upward to its full travel.

    3: while the ram with the case is fully up, start screwing your seating die down until you feel it contact the case.

    4: then back the die off (up) 1/8th to 1/4 turn and lock the nut.

    This should clear up your problem.

    Jeff
     
  5. jrs

    jrs Member

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    Sounds like you may have too much neck wall brass.

    Since the empty cartriage chambers ok, and I am assuming you are using a quality factory bullet that mic's out at the appropriate diameter then here's what's happening and how to fix it.

    The resizing die (either neck or full length) is sqeezing the outside of your neck to a diameter much less than necessary, then the expander ball, on the upstroke is stretching your case neck to the size the die maker felt was correct for your application. Typically an inside diameter of about 0.002" less than the outside diameter of the bullet. None of these things have address the thickness of the case neck which grows after every firing.

    Generally the effect is not noticable for the first few firings of a case, but in the case of a tight necked chamber (a good thing!) and thick walled brass it could happen on the first reloading.

    The correction is to either inside ream or outside turn the case neck to a thinner thickness. I have found that with outside turning it is much easier to control the amount of brass that is removed. Inside reaming will sometimes be necessary to remove "The Dreaded Doughnut" which is a region near the transition between the neck and the shoulder on the inside where outside turning can't reach, that may become quite thick. If your bullet doesn't touch this area then it has no noticable affect, but if the seated bullet does touch it, most likely it will show up as increased outside diameter right at the neck shoulder junction after the seated bullet forces the excess to the outside. Should only happen with heavy for caliber and/or flat based bullets.

    One last thing - remember that if you turn 0.001" off of the outside you have changed the diameter by 0.002" (half on each side).

    Hope this helps!
     
  6. Elk Chaser

    Elk Chaser Well-Known Member

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    Thanks for the suggestions. I think I'll start by start by pulling the rounds and re-sizing per Broz's recommendation. Should I be aware of anything or extra cautious while decapping live primers? This will prove to be quite a learning experience that's for sure, I'm just confused as to why the 21 rounds i loaded last Sunday shot just fine and then this go round with the same dies and same set up I'm running into this problem. Thanks again, I hope everything works itself out!
     
  7. ROBSTER

    ROBSTER Well-Known Member

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    Had a simular problem with a 308. I was loading them for a semi auto and was crimping them then I got a encore pistol and was using non cannilured bullets and was crushing the brass just enough that it would not chamber after several days of playing and pulling my hair out I realised that I was still crimping them and had to adjust the seater die up a few turns.
    robster
     
  8. Broz

    Broz Well-Known Member

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    You should be fine while decapping. I would wear safety glasses to be sure and remove powder from the bench area. But I have done this many times and never had one go off.

    This is why a redding T-7 turret press is so nice. Once the dies are set to perfection you never need to remove them. Most likely the first time you loaded them the die was a few thousands higher. Plus your brass likely grew a few thous. with the last firing.

    You will be fine and back on track soon. Plus if this does cure your problem you have now learned something. Problems are a pain but they always teach me to research and learn.:)

    Jeff
     
  9. SBruce

    SBruce Well-Known Member

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    Some dies are made that the decapping pin can be removed. If it cant be removed, you can sometimes move the whole rod/expander/de-capper up in the die so it doesn't touch the primer. You would still be able to resize the brass but it wouldn't knock out the primer. I don't recall which dies are what way though?

    I usually use a hand de-capper myself, better feel of what's happening IMO.

    One other suggestion, not really relevant here if the brass fit before the bullet was seated, but it will still be usefull.
    I highly recommend an RCBS Precision Micrometer for setting up your FL Sizing die. It will allow you to just barely bump the shoulder back when you resize. The common directions for adjusting the die don't always fit every rifle, and alot of times; the brass is being oversized or undersized for your chamber. The Precision Mic will remedy this, and serves a few other purposes too. It's not expensive.
     
    Last edited: Sep 17, 2010