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Thread: what has happened here then? FL Sizing die problem

  1. #1

    what has happened here then? FL Sizing die problem

    I have recently acquired some reloading bits and bobs to replace my trusty lee handloader (which I am still using!)

    Lee press (yes I know!) and RCBS FL and Seating dies, Norma brass

    I have not needed to or tried to reload with it yet as I am still just getting set up and used to the idea of using a press.
    posted a question about the seating die and the crimp action it imparts in another thread but this is vexing me!

    The FL die was fine and I test sized a couple of old (lubed) cases and deprimed/sized them perfectly well.
    on swapping the die back in after practising some seating it didnt do the resizing as before.

    The case is very tight on the final 1/2" and it created a ring on the shoulder. Neck size appears fine and the shoulder is in line with other cases
    I have also tried with the decapping pin and expander pin removed and it did the same.

    The top of the die has a screw fitting which doesn't appear to move on mine, I am not sure if it is meant to and whether this would impact the symptoms I have

    I mean the second knurled fixture on the bottom die in this pic:




    have inspected the die internally as best I can and it is clean and clear, cases have been lightly lubed (inside and out).

    I did have a thought that I may have run an already resized case back through twice (in error whilst playing around) would I get this? (ball pushing neck down slightly into case meaning it was tight on upstroke leaving the ring mark?)
    Pretty sure this is what has happened but thought I would ask!

    Seems fine now so I am just going to leave it alone!

    this is the normal neck after resizing:


    This is the one that has a slight bulge and clear witness mark:


    My expander/decapping pin has a gap with exposed threads between main pin and expander. this seems a bit of a pants design. is this normal and is it designed like that for a reason?


  2. #2
    Try backing your die off a tiny bit, lube the case well with good lube. (and the case mouth!) Are you using the same lot brass?? That bit oif exposed thread on the expander is of no consequence and has been found on RCBS die sets for a very long time, pants or not.

    That knurled bit the expander travels through does come off but will probably need a set of pliers to break loose the first time. I always do.~Muir

  3. #3
    Tell us how you oringinally set the die up - from the picture it looks like it is screwed down too far or........... did you forget to set it up with a shellholder in situ?

  4. #4
    Take a fired case ............................. unsized and measure the neck diameter at the mouth and ten at the juncture of shoulder and neck. I am thinking that you have tapered necks and the size by the shoulder will be quite a bit larger that the diameter at the mouth.

    I just checked one fired in one of my BSA's and the case tapers 0.002" measuring 0.308" at the mouth and 0.310" by the shoulder. Went outside got my RCBS 270 Win dies and out the sizing one in the Rock Chucker after a quick roll on the lube pad then a wipe on the inside of the neck with the lubed cotton bud kept in the lube pad tin.

    neck O/D now measures 0.300" and the neck by the shoulder measures 0.3005". If one looks very closely yes there is about 0.020" that the die barely touches. However it requires an eyeglass to actually see it on this case.

    In your case I suspect the neck of the chamber is tapered and a bit generous at te rear by the shoulder. Of course it's difficult to tell froma photo with no measurements. Hopefully I am wrong and it just a slight die problem.

  5. #5
    I had a Lee die that did this for .303Britsh cases. In my case it was the portion of the die that squeezes the neck onto the expander /decapper pin that needed a slight change (widening slightly) and on the Lee is doable with a thin knife inserted to open it out a bit. I would think that if the sizer is fixed it may be that you have it too far down and as Muir say's - back it off a few turns before trying again.

  6. #6
    no, it doesnt appear to be too far down.
    set it up as follows:
    shellholder in place,
    ram up full stroke (cammed over!)
    screw die down to touch shellholder
    release ram
    1/4 turn more
    tighten collar
    test ram

    I did try altering the die depth but it didnt impact much.
    I am assuming from looking at it that the only thing screwing the die further down does is increase the pressure on the ram at full stroke?
    you cant compress tool steel and the die depth doesnt appear to be reflected in the profile of the resizing...or am I wrong?
    Last edited by bewsher500; 26-06-2012 at 13:34.

  7. #7
    Measure the neck of a fired and unsized case!

  8. #8
    Quote Originally Posted by bewsher500 View Post
    no, it doesnt appear to be too far down.
    set it up as follows:
    shellholder in place,
    ram up full stroke (cammed over!)
    screw die down to touch shellholder
    release ram
    1/4 turn more
    tighten collar
    test ram

    I did try altering the die depth but it didnt impact much.
    I am assuming from looking at it that the only thing screwing the die further down does is increase the pressure on the ram at full stroke?
    you cant compress tool steel and the die depth doesnt appear to be reflected in the profile of the resizing...or am I wrong?
    When you say "Cam over" do you mean that the ram goes up all the way and then drops on the back side of the cam stroke? I hope not.

    Try bringing the ram to the very top-dead-center of it's stoke and screw the shell holder down until it just touches the shell holder. Don't screw it down any more. Just size it. I never screw it down harder than just touching the shell holder.~Muir

  9. #9
    the ram doesnt appear to drop but there is a point in the arm stroke where the ram hits the top of its travel but there it is still possible to push the arm 1/2" or so

    I read that this is referred to as the "over cam"


    Think I know what has happened.
    It has to be the resizing of an already resized case. (just playing around with a limited number of cases I was happy to scrap if they were screwed up....which this one is!)

    the expander ball is pushing the neck into the shoulder slightly giving the bulge which then doesnt fit the shoulder profile of the die.
    the arm stroke then feel stiffer than normal as it reshapes the shoulder back leaving the witness mark

    will see if I can replicate it to prove my thinking later
    Only reason I am considering the FL sizing is I have two .270's and the once fired will only work from rifle 1 to rifle 2, not the other way round

    I think the whole expander ball method of inside sizing is mechanically flawed anyway.
    IMO the case neck should be supported in the die and the ball should then be pulled back through the case giving uniform neck thickness and fixed inner and outer diameter dimensions.
    excess brass would present itself at the neck to be trimmed

    going to go with a collet die I think (or stick with my zero error hand loader!)

    thanks everyone anyway

  10. #10
    Cam over was something that my old Hornady press would do. It would hit top-dead-center and then fall away slightly like a piston on a crank shaft. It's very slight but it was there. If that is where you are setting your dies, it's sizing too much. Collet dies are great. I use them quite a bit.~Muir

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