Trouble bumping shoulder - bad reamer?

Discussion in 'Reloading' started by drenge, Aug 30, 2010.

  1. drenge

    drenge Well-Known Member

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    Guys I need help on this on. I have a redding body die for my 7mm Rem Mag. When my headspace measures 2.122 it gets tough to close the bolt. I set the die up by screwing the die down until it contacts the top of the shell holder. I then tighten it down and run a lubed case through it.

    The headspace measurement doesn't change after I've run the ram all the way up to the top of a stroke - and my shell holder is hitting the die! So how do I bump my shoulder back .002 if my shell holder is already up against the die and I can't go any further?

    Could it be that my gunsmith used a bad reamer? I would like to get my headspace down to 2.119 where it seems to fit just fine. I've also order the redding comp shell holders for the 7mm rm - but obviously it won't matter if I'm already against the die (or will it?)

    Any suggestions?
     
  2. BobbyL

    BobbyL Well-Known Member

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    No its the die thats the problem. Take off the bottom of the die untill you get the bump and it will fix your problems. It doesnt need to be pretty just enough to get the bump you need. They also make offset shell holders that will help you out.
     

  3. drenge

    drenge Well-Known Member

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    How should I take of the bottom of the die? Just sand it down? I did order the comp shell holders that are made in .002 increments - will those help?
     
  4. bigngreen

    bigngreen Well-Known Member

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    Wait for the shell holders so you can set it up right and have good shell holder to die contact at the end of the stroke.
     
  5. BobbyL

    BobbyL Well-Known Member

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    You can wait. Sanding off the bottom of the die will not hurt the accuracy of your reloading. It only changes how far it bumps the shoulder. Just make sure you take off enough that it doesnt hit the shell holder anymore after you get enough bump.
     
  6. drenge

    drenge Well-Known Member

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    Got it! Makes sense. Thanks for your help.
     
  7. BobbyL

    BobbyL Well-Known Member

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    No problem. You dont need shell holder to die contact but just make sure you dont take a bunch of of it or it wont resize the web of the case enough. Its ok to have .005 or .01 clearance but no more then that.
     
  8. drenge

    drenge Well-Known Member

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    I've been taking a few measurements and compared against saami spec. The 7 mm rem mag should have a headspace of 2.125 and my brass is getting tight at 2.121 which means my gunsmith may not have cut the chamber deep enough.

    I called redding and they said their tolerances are very tight on both their shell holders (1/8 inch deep) and their dies. The comp shell holders actually start deeper than their standard shell holder (1/8) so that will not fix my problem.

    The only solution is: a) cut the bottom of the die down a few thou; or b) have my smith cut the chamber a little deeper.

    I'm inclined to have my smith cut the chamber deeper after hunting season because I am noticing a small cut along the shoulder of all of my tight fitting brass. Meaning there is some kind of imperfection along the shoulder inside my chamber.

    Thanks again for your help.
     
  9. boomtube

    boomtube Well-Known Member

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    If factory ammo routinely chambers it's highly unlikely your chamber is a problem. Nor, point of fact, is it likely there's anything wrong with your FL sizer or shell holder. Your goal of achieving a specific point for the shoulder location is moot, headspace is a range, not a specific point. What you see in books is the maximum case shoulder location and that ignores the full chamber tolerance range. Part of what handloading is all about is making our ammo fit our chamber, not the other way around. Die touching a shell holder or not isn't the issue, how far back we set the shoulder is. Redding's "competition" shell holders are no solution because they are thicker, not thinner. All they can do is reduce the amount your cases can enter the die and that will make your present difficulties worse.

    You likely aren't sizing them quite enough, I'd bet that if you turn your sizer down another 1/16 turn (about 4.5 thou) and do your sizing again the "problem" you are experiencing will dissappear. There is no reason to set a fired case shoulder back at all from its fired location. It has expanded to fit the chamber and shrunk back at least 1 or 2 thou from that length, all we need do is restore the fired position when FL sizing.

    Many reloaders follow basic size die "instructions" by touching a shell holder plus some small additonal turn without a case fully inserted into the die. That only provides a starting point, it can't possibly accomidate the small variations in die and holder tolerances or the significant variations in press spring. A handloader has to tune his sizer by trial and error to accomplish what needs to be done, otherwise he's just doing his loading steps by rote as the factories do. I'm not looking up the headspace tolerance for a 7 mag but for all bottle neck cases it's typically a spread of about 7-9 thou at the shoulder (forget any belt or rim, always resize to the shoulder of a bottle neck case).

    IF you really need to shorten the mouth end of your sizer, do it by sanding or grinding (you can't file that case hardened metal) and a fine grit paper on a belt or disc sander is great for this work. First remove the decapping stem and measure the die body length accurately. Then grind/sand off a couple of thou at a time until you've removed just enough to set the shoulders back as necessary. Do no more or you WILL need the thicker shell holders!
     
    Last edited: Aug 31, 2010
  10. bigngreen

    bigngreen Well-Known Member

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    I've ground a few dies and then started just sanding down the shell holder, turn it upside down on a piece of wet/dry and go at it.

    I stopped grinding and started setting things to spec and have yet to grind on anything, just set the die to where the handle cams over and I get the shoulder bumped back just over .001 and I'm not over sizing anything, works like someone planned it to happen that way :rolleyes:

    I had a rifle that I went though this same kinda thing with and it wasn't the shoulder that was the problem it was the chamber was over sized. So I thought I was grinding down the die so the shoulder would set back but in reality I was running the brass deeper into the die and getting it sized down to where I needed it, what was happening was that I had to set the shoulder back almost .010 to get the body sized down. Just a thought.
     
    Last edited: Aug 31, 2010
  11. drenge

    drenge Well-Known Member

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    Very good info guys. I'll reset the die then I'm going to check my shell holder and make sure it's not too thick. If I have to I'll grind the shell holder and then the die.

    Thanks again
     
  12. BobbyL

    BobbyL Well-Known Member

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    Yes as long as the chamber is good in the rifle and not causing problems the die needs to be worked on. I have had more then a few factory dies that did not work and its easy to see how them being off just a little bit could cause problems quickly. When i chamber my own dies i make sure to set them up so i can quickly hit the shell holder with the die and start sizing with a .002" bump. As long as your not trying pressure bump them hard against the die with the shell holder you will be fine just to grind it off. I prefer to do it with a lathe so i know im keeping everthing square but then again i have the equipment to do so. Good luck with your problem i hope that you find a easy answer.

    bobby
     
  13. boomtube

    boomtube Well-Known Member

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    "If I have to I'll grind the shell holder and then the die."

    It's your stuff to do with as you wish but I see no benefit from grinding on both the shell holder AND die.

    If setting your die down a tad doesn't work it would be good to completely "paint" a cartridge with a Magic Marker, chamber and withdraw it then check for contact rubs. At least you will then know if it's from the shoulder or body being too large.
     
  14. groper

    groper Well-Known Member

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    yep, the situation your in goes like this;

    your smith chambered your rifle with a tight headspace clearance for that cartridge, which is a good thing because you dont work your brass as much between firing and sizing.

    your die was cut on the deep side of the specd dimention for that cartridge and would most likely work if you had a sloppy chamber.

    Die makers should take notice of this, as many of us have tight chambers and face this problem, myself included. There is no reason we should be forced to grind the end of the die down to be able to bump. There is ample clearance to work with in this area between the case head and body of the case above the rim of about 150thou! - well within the limits of all headspacing possibilities. I wish they would take notice and stop selling dies like this...
     
    Last edited: Aug 31, 2010