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Thread: Mandrel v bushing dies on case necks?

  1. #46
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    Hey I just noticed something else.... this is the first vid or pic of Jackie where he don't have bandaids (or duck tape) on something or another.... ain't even got a black nail there man, looks like you been being careful!

  2. #47
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    Quote Originally Posted by Al Nyhus View Post
    I experimented with the mandrel method when shooting the 30 WareWolf (basically a .165 short 308 Lapua) my HBR gun. And no...it was not with any sort of Lee collet die lash up.

    Initially, it seemed to show some slight accuracy improvement.

    What I was actually seeing was that the mandrel was a bandaid for how bad the necks I.D.'s were. They were round but also tapered. Like this, top to bottom (exaggerated, if only obviously ):



    After finding that, I made the neck I.D.'s perfectly round the on my fired cases and tested that. The results on previously neck turned cases was a train wreck. But on new cases, where the neck I.D.'s were made perfectly round before outside turning....the accuracy was better than it had ever been especially at 200 yards. Beggar 10's @ 200 became solid 10's and the 'almost-a-10' 9's @ 200 became beggar 10's. Grand Aggs are won or lost @ 200 and the Grand wins came with more regularity after that.

    Since that, inside case neck work became part of my BR case prep routine, carrying over to the 30BR cases and even to the 30 WolfPup with the .085 length neck.

    Does every case need it? It depends. If necking up or down, I do it. I did it on my 6PPC with the 220R cases and found nothing with both barrels. But on my 22BR, there was an improvement. My 20 Practical (necked down Lapua 223 cases) shows the same characteristics. I haven't fixed them yet, but I will and will test them next Spring.

    I don't compete any more in registered BR tournaments but still consider the case neck I.D.'s to be a critical part of case prep if you're looking for BR level accuracy.

    Good shootin'. -Al
    Great info, Sir. Thanks

  3. #48
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    Quote Originally Posted by jackie schmidt View Post
    The way most shoot the popular Short Range Benchrest rounds, bullets never get any where near the donut that will, regardless of our best efforts, form at the neck/shoulder junction after several firings.

    That is why I consider it a non factor.

    However, in disciplines where longer bullets are used, especially in a shorter throated chamber, it can be a huge issue if the shank of the bullet gets into the donut.

    The best solution is to throat your chamber for a specific bullet so this never occurs.
    Good point, Sir. Thanks

  4. #49
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    Quote Originally Posted by michaeljp65 View Post
    There is a new machine out called the IDOD. Turns the inside at same time as outside. https://www.youtube.com/watch?v=Qx6MNdIijxg
    That is really cool. Thanks

  5. #50
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    Here's the way I turn necks (Lapua Brass 6ppc)

    I mount a expanding mandrel in the set-true chuck and dial the thing to zero. I made a pusher that goes in the tail stock and use it to push and expand the case. The mandrel drives the case because it's a tight fit. I turn the brass with a single point tool. The pusher has an extraction tool that fits in the groove of the case to pull it off when I'm done. The necks come out perfect and there is no scoring on the inside because the case never turns on the mandrel. No heat issues to deal with. I have stops set on both sides of the carriage and a dial indicator on the tail stock so everything repeats.
    The pusher has a pilot to fit the primer pocket. It's a PITA to set up but works well.

    Richard

  6. #51
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    So, Jackie..... those are FIRED cases and they spin inside the fixed shellholder?

    I just realized what you're doing. Friggin' BRILLIANT, I'd a' never thought of spinning the case with it captured, but essentially free with several thou tolerance.

    I have a setup where I insert and support the tightly fitted mandrel COMPLETELY BAZZACKWARDS of what you're doing. which essentially accomplishes the same mechanical functions but....gotta' drive the case etc....


    but'chyoo'


    BRILLIANT!

  7. #52
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    Quote Originally Posted by Richard View Post
    I mount a expanding mandrel in the set-true chuck and dial the thing to zero. I made a pusher that goes in the tail stock and use it to push and expand the case. The mandrel drives the case because it's a tight fit. I turn the brass with a single point tool. The pusher has an extraction tool that fits in the groove of the case to pull it off when I'm done. The necks come out perfect and there is no scoring on the inside because the case never turns on the mandrel. No heat issues to deal with. I have stops set on both sides of the carriage and a dial indicator on the tail stock so everything repeats.
    The pusher has a pilot to fit the primer pocket. It's a PITA to set up but works well.

    Richard
    Richard, I always turn a new mandrel every time I decide to turn necks. But then, I always have a lot of material laying around.

    I usually do 100 at a time. As you can see, I have a mist cooler spraying on the mandrel to keep the set up cool and to lubricate the tool.

  8. #53
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    Turned out to be an interesting thread. Thanks
    I probably learned something.

  9. #54
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    Similarly...

    Quote Originally Posted by Fred Bohl View Post
    I've waited to see were the replies might go before my own reply.

    My simple answer is yes I have. I neck size using a bushing that produces a neck of slightly smaller ID than desired (0.001 under) then an expander die to open the neck to the desired ID size. Testing over the 4 cartridges I load for shows slightly smaller groups for those mandrel sized than those just bushing neck sized. Note that the reduction in group size is very small but for me it is worth the added effort.
    I've tried it in several different scenarios too. Where I'd normally use a 257 bushing, for example, I used a 256 bushing and resized the case body too. Then ran them through the expander mandrel that is in my K&M neck turning kit.

    The results were lower and much more consistent seating pressure for all cases. The results on the target showed that bullets that are seated deep into the neck or slightly more were consistently accurate for 300+ yards such as 90-103gr bullets from a 6br or 6xc. For the short range 100-200yd 6ppc or 6 Grendel did NOT show any dramatic and positive affect towards smaller groups on a consistent basis. In fact one 6ppc the groups opened WAY up, and on another 6ppc I have they stayed pretty much the same but NOT better.

    It's worth a try for me just because I learned something from it. JME. WD
    Last edited by WyleWD; 12-19-2019 at 08:04 AM.

  10. #55
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    Jackie, what

    type of coolant are you using?

    Richard

  11. #56
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    Wilcox, PA
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    Need info jackie

    Jackie how often do you change cases oh firings bill b

  12. #57
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    Quote Originally Posted by Richard View Post
    type of coolant are you using?

    Richard
    http://benchrest.com/attachment.php?...1&d=1576701691

    I use this because it is what we use in our big band saws.
    Attached Thumbnails Attached Thumbnails Click image for larger version. 

Name:	03120AEC-61E6-4F94-B093-8C50C52B1CA4.jpeg 
Views:	93 
Size:	2.25 MB 
ID:	23181  
    Last edited by jackie schmidt; 12-18-2019 at 04:05 PM.

  13. #58
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    Thanks Jackie

    Nt

  14. #59
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    Quote Originally Posted by WyleWD View Post
    I've tried it in several different scenarios too. Where I'd normally use a 257 bushing, for example, I used a 256 bushing and resized the case body too. Then ran them through the expander mandrel that is in my K&M neck turning kit.

    The results were lower and much more consistent seating pressure for all cases. The results on the target showed that bullets that are seated deep into the neck or slightly more were consistently accurate for 300+ yards such as 90-103gr bullets from a 6br or 6xc. For the short range 100-200yd 6ppc or 6 Grendel did NOT show any dramatic and positive affect towards smaller groups on a consistent basis. In fact one 6ppc the groups opened WAY up, and on another 6ppc I have they stayed pretty much the same but NOT better.

    It's worth a try just because I learned something from it. JME. WD
    Great info. Thanks

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