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Thread: Concentricity variations with bullets/seating

  1. #1

    Concentricity variations with bullets/seating

    It doesn't come as a surprise, but measuring F/L sized brand new Norma MSch 6.5x54 brass, concentricity between neck/body is max. .0005"/ 1/2 thou.
    Bullet seating, using a Redding seating die with the correct 'dome' insert for seating a Hornady #2640 160gn RN bullet, produces even taking the very best care in technique when seating,
    concentricity variations of - greatest majority within .0015" - .002" run out & some (5%) @ .003" run out, but 5% greater than .004" run out.

    I have no idea why there are these variations, but guess it's either the bullet that's the problem, or harder to determine, but something I did while seating the bullet.
    Odd!
    Last edited by deeangeo; 10-12-2016 at 14:46.
    Blaser K95 Luxus Kipplaufbüchse .25-06Rem. Schmidt & Bender 8x56, 110gn Nosler Accubond = Game Over!

  2. #2
    You maybe used a die that didn't centralize the bullet with the case along the axis. Did you insert the case deep enough into the die before adjusting the insert to give the required COAL?
    Or -- Are you getting too much resistance to inserting the bullet into the neck? - You can have too much neck tension.
    You can make bullet insertion less problematic by using a case neck expanding die - I use a Lee Expander - K3 when loading flat bottomed bullets with sharp corners on the base. Just a slight tweak is all that is needed. I then use the Lee Factory Crimp die to nip it back in place & get the neck tension.

    Ian

  3. #3
    I don't fully understand how you're measuring this, but might it be caused by the sides of the bullet being significantly tapered. Being an unashamed and grateful copycat, I am using the same materials...although am not yet concerned about concentricity beyond what i can see by eye.
    I did a few rounds with new Norma brass and didn't bother FL sizing it because it seemed ok as supplied. All I did was use a bullet turned the wrong way round to even out any visible squishing of the case mouth and ensure the internal diameter was consistent. If the cases are still good enough to make you happy after sizing I can suggest the following:
    Getting back to the point. The Hornady bullets were only .264 at the base and tapered an amount that would certainly allow the loaded bullet to be out of whack by .004 if the die had an internal diameter of .264. Might it be worth trying a paper patch or something ...see primitive diagram...Click image for larger version. 

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    The figures on the diagram are approximate from memory, but I hope you get the idea.
    Last edited by Apthorpe; 10-12-2016 at 14:22.

  4. #4
    I haven't found my Lee expander die to be as great a success as the use of a vld chamfer tool & yes, I also use a Lee FC die to even out neck tension.

    The Redding dies I use are generally fine, with the seating die especially suited to the RN bullet this cartridge utilises. Also, no, I don't feel any great resistance when the bullet is inserted to case neck. In fact the feel of bullet entering case neck is really rather smooth.
    Whether or not useful, (there are arguments for & against) I also rotate the case/bullet when seating. I do so on the basis it can't do any harm and may be helpful.

    Still however, these slight variations occur & although not a huge issue, just a tad frustrating they occur at all.
    So, just wondering if I'm missing something.....other than getting a custom seating die made, which, for this ninety odd year old rifle, is probably carrying matters rather far.
    Blaser K95 Luxus Kipplaufbüchse .25-06Rem. Schmidt & Bender 8x56, 110gn Nosler Accubond = Game Over!

  5. #5
    Apthorpe I always F/L size new brass. Just something I've done from the start thirty odd years ago.
    If you're using an inverted bullet to even out neck dings, your neck tensions will not be as they should be had you used a die with correct expander rod.
    The die squeezes in the case neck and the expander rod re-opens the neck to correct internal dimension to grip the bullet properly. The bullet is a thou or so greater dia. than neck ID so your neck tension on those cases you treated to the inverted bullet will be a 'looser' fit.

    I use a Sinclair concentricity guage to check run out. It's a simple enough tool to use & gives helpful, if sometimes frustrating information. However, in this instance, the case neck/body run out is not the problem. The bullet may be the problem, but I cannot determine if my seating technique or the actual bullet is the problem.
    Blaser K95 Luxus Kipplaufbüchse .25-06Rem. Schmidt & Bender 8x56, 110gn Nosler Accubond = Game Over!

  6. #6
    George have you tried pushing the bullets straight? I have often thought that the Hornady gauge/straightener is a good idea. ( CONCENTRICITY TOOL
    SKU: 050076)Maybe one of these days I'll make something similar.
    In the meantime my reloads shoot better than me (wonky or not so) it isn't a big issue.

    Ian

  7. #7
    Quote Originally Posted by Yorric View Post
    George have you tried pushing the bullets straight? I have often thought that the Hornady gauge/straightener is a good idea. ( CONCENTRICITY TOOL
    SKU: 050076)Maybe one of these days I'll make something similar.
    In the meantime my reloads shoot better than me (wonky or not so) it isn't a big issue.
    Ian
    No Ian I haven't tried that as my guage doesn't have that facility. I suppose using a guage that does this can help, but I guess a re-crimp would be necessary to reset the neck tension, Yes/No??
    Blaser K95 Luxus Kipplaufbüchse .25-06Rem. Schmidt & Bender 8x56, 110gn Nosler Accubond = Game Over!

  8. #8
    A recrimp may be in order - just to re-nip it in its new location.

    Ian

  9. #9
    I just had another thought. Does the profiled die bullet pushing insert have full contact on the bullet nose? It would centralize better if it has anular contact rather than by pushing with a ball joint type of contact.

    Ian

  10. #10
    Try the same combo in another make of die.borrowed of course.i,m spitballing being a noob.
    DONT START

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