Two Bullet Seating Scenarios - Which Is More Accurate?

Discussion in 'Reloading Forum (All Calibers)' started by kvd, Aug 2, 2017.

  1. kvd

    kvd Silver $$ Contributor

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    Scenario One. One pushes the bullet into the case neck, making the seating depth adjustment on a micrometer scale which stops the seating stem from downward travel. This would be on a seating die like a Wilson or a Sinclair/Wilson.

    Scenario Two. One pushes the case and bullet up into a seating die with a press until the bullet contacts the seating stem and the case is pushed onto the bullet until it reaches the top of the press stroke. Most seating dies like Redding, RCBS, Forster, work this way.

    In one instance the bullet is in motion and the case stationary while in the other, the bullet stops and the case continues in motion until it stops.

    Is one method inherently more accurate from the standpoint of maintaining a known fixed distance of a given bullet to the lands of the rifling?



    Ken
     
  2. Raythemanroe

    Raythemanroe Bullet Whisperer

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    I have used both with the same gun,brass and bullets.. Best results were with a chamber die/Wilson.. I don't really care to as the why of it all..


    Ray
     
  3. jsthntn247

    jsthntn247 Silver $$ Contributor

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    #1 because you can't put a seating force gauge on scenario #2
     
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  4. mikeeg02

    mikeeg02 Michael Glantz Gold $$ Contributor

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    Scenerio one sounds like an arbor press style, scenerio two looks like a standard cam press style. If I am reading your description correctly.

    I try to shoot competitively, and always measure every loaded round and will only tolerate .0005 difference. I started with Redding comp micrometer die for my rcbs press. I had a bit if varience and would need to seat bullets 2-3 times. I'd seat them once, sort them that way and find how far off they were and seat them a second time. Usually the second time they worked, but sometimes they needed a third seating. After talking with Redding, the fella I spoke with recognized what I was doing, and suggested allowing the final bit of travel of the press handle to be done by gravity, rather than by force because the cast metal does give a little when pushed. That helped and got my loaded rounds typically within. 001.

    I picked up a set of Sinclair/Wilson dies and an arbor press, and the results are amazing. I still measure every round, but they are almost always on the money, and sometimes vary .0005, and very rarely do I get one that needs seated again. Which I can only assume is from a different bullet. (I only sort bullets by weight)

    Having said that, you cannot adjust the micrometer on mine while seating a bullet, because it has detents and it clicks. It's super nice because it has .0005 detents. Money well spent. IMO.
     
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  5. mikeeg02

    mikeeg02 Michael Glantz Gold $$ Contributor

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    Also, there's no doubt that one can be happy with the Redding style with a cam press, they key is consistency. I've loaded a lot of rounds with one, and have a friend thats an exceptional shooter, who just refuses to spend the money on dies again for an arbor press, when what he has, has worked for so long.

    For me it saves time to use an arbor press.

    I think the biggest advantage of the Sinclair/Wilson die in a arbor press style is the stop is ALWAYS at the exact, same point(Unless you have dirt or oil or some foreign material on top of the die). The only way YOU can change seating depth when set is to run it in so fast with very light neck tension that the bullet continues to slide after you have hit the stop. Again, consistency is the key, as it is the key to many successful hand loads. And since I ONLY weigh bullets for sorting, I do still get that 1 in 15 or so that needs seated in a bit more because the bullet was that much different.

    Hope that helps.
     
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  6. kvd

    kvd Silver $$ Contributor

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    I have those Sinclair/Wilson seating dies in 6PPC and 6 BR Norma. They are really nice. Wish they made one in 7 RSAUM.

    Ken

     
  7. 264WM70

    264WM70

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    Ken,

    If you want one in 7 RSAUM, buy a 7 mm blank Wilson seating die and have the Wilson blank reamed with a 7 RSAUM reamer (preferentially with same reamer used to ream your 7 RSAUM chamber). If you want the micrometer top, Sinclair makes an add on micrometer top for the blank Wilson seating dies that works really well.

    Joe
     
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  8. kvd

    kvd Silver $$ Contributor

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    Thank you for the info Joe. I'll look into that.

    Ken
     
  9. newbieshooter

    newbieshooter :-) Silver $$ Contributor

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    Wilson sells blank seating dies with micrometer top:
    http://www.brownells.com/reloading/...icrometer-top-seater-die-blank-prod88119.aspx
     
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  10. kvd

    kvd Silver $$ Contributor

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  11. T-shooter

    T-shooter

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    I use a heavy cast iron Lee press and a Redding Competition seater. I can vary the seating depth based on how much force I put on the handle. The difference between a light touch just feeling the ram bottom out and putting maybe 10-15 lbs pressure on the handle is as much as .005". To seat to the same depth (or distance to the lands) I set the die to never go past my setting with a light touch. Then if it needs to go deeper, a bit more force does it. Each round is checked with a Hornady comparator and adjusted as necessary. I never depend on the press or die for a final seating depth in any ammo that is loaded for accuracy.
     
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  12. kvd

    kvd Silver $$ Contributor

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    T-shooter,

    What you describe with your technique is what I'm wondering about. Does play in the press and maybe even the cartridge length figures more prominently in scenario 2 than in scenario 1 or does the bullet end up in the same place relative to the case neck either way.

    The problem is, there is no way to measure from the point on the bullet ogive that is the same diameter as the rifling lands forward to the lands as we seat bullets. One can measure Cartridge Base to Ogive (CBTO) and compare this dimension with a dummy round but are variations in cartridge length and bullet shape throwing this measurement off. We are essentially measuring everything behind what we actually want to measure and the bullet may not be positioned where we think it is in relation to the lands for a given round. Seems to me that adjusting a Wilson type die in or out is the better way to go.

    Thoughts?

    Ken
     
  13. T-shooter

    T-shooter

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    Usually, the bullet will end up within .001" if I apply the same pressure each time. If a case neck happens to be a bit tighter/looser, or the brass a bit more/less springy, then that may vary. I use dry graphite in the necks. This press doesn't cam over and is reasonably tight and only about 1-1/2 years old. I screw the quick change adapters down tight past the detent. Still, there must be a little flex somewhere. All the cases are trimmed to length and neck turned. As for seating depth, I measured one from the chamber and made a dummy cartridge with the came bullet. Then use the Hornady gauge and match everything to it. The inside of the insert is .298", .010" under the bullet diameter. I know what you mean about variations. Still, this method, with what I have, should be better than just relying on the seater itself which contacts the bullet much farther out. How would the Wilson die compensate in small variations in the bullet ogive? I do sort bullets by weight (better than nothing). The last 100 Berger 200.20X's varied in weight from 200.04 grains to 200.32 grains (Lot# D024). About 1/2 were between 200.018 - 200.022. The rest I'm using to work up a load.
    Press1.jpg
     
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  14. newbieshooter

    newbieshooter :-) Silver $$ Contributor

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  15. Stralyanshooter

    Stralyanshooter

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    The Lee dead length bullet seating dies give me really consistent CBTO lengths used in a small RCBS press. Set up as instructed so the shell holder comes into firm contact with the base of the die they all measure to within .001. No vld stem needed either with these dies. Simple, cheap and effective. YMMV..
     
    Last edited: Aug 2, 2017
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  16. Don

    Don Gold $$ Contributor

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    John Whidden just Won at the Natioal Matches
    What Dies did He Use ?

    I love to see all this hair splitting
    I also love this little line !
    " It is not the Arrow it's the Indian "
    Holden and follow thru !
    Good Luck ......
     
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  17. ballisticdaddy

    ballisticdaddy Silver $$ Contributor

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    Whidden has won quite a few major events but his whole reloading theory is a bit different than most. He does not use ANY die to get his final seating depth, he seats them all long and lets the rifling do the final seating as he closes the bolt. Not exactly what the OP was asking.....
     
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  18. kvd

    kvd Silver $$ Contributor

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    Interest info ballisticdaddy. I've heard of BR shooters doing this with light neck grip. Would certainly take the guesswork out of wondering if the bullet is jammed into the rifling or not.

    Ken
     
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  19. kvd

    kvd Silver $$ Contributor

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    Those are very consistent weights. I've not sorted bullets by weight but only with a Bob Green Bullet Comparator which sorts more for shape.

    Ken
     
  20. ballisticdaddy

    ballisticdaddy Silver $$ Contributor

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