Ahhhh, the differance a little neck tension makes.

Discussion in 'Reloading' started by Michael Eichele, Dec 17, 2006.

  1. Michael Eichele

    Michael Eichele Well-Known Member

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    After some experimenting recently playing around with neck tension I figured out that identical loads except for NT shoot differantly. I never thought .001-.002 NT made a hill of beans of differance on accuracy until now. Below are 4 pictures of 2 differant loads. My 200 ACCUBOND load and my 178 AMAX load. The only differance in the 2 groups of each is NT. The 200 AB used .003 and .004" NT and the 178 AMAX used .001 and .003" NT. These are not the only groups that have done this. Scince I have started playing around with NT, every time it has changed it. If I leave it alone, the groups stay the same whether good or great.


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  2. victor

    victor Well-Known Member

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    Meichele,

    Looks like a significant improvement.
    Can I ask how you adjust neck tension. I assume you are using the "S" type dies for which you can oder various neck tension dies. These are the ones with the neck die that floats. Is this correct and if so, do you ever have trouble with concentricity (loaded bullet being out of round with case body).

    Thank,
    Vic
     

  3. davewilson

    davewilson Well-Known Member

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    i can see going from 1 to 3 NT making a little difference but i wouldn't have thought going from 3 to 4 would do much.did you say you've repeated this a couple of times? by the way, very impressive groups you have there.
     
  4. wapiti13

    wapiti13 Well-Known Member

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    Vic, The whole point of the neck bushing is to keep everything floating and centered. Assuming a centered neck in your chamber, the Redding dies will size correctly. Bullet seating allows a bullet to enter offline, which is why most use the benchrest Redding seating die. Run outs can be kept at .001 with care. I assume that you can get "too tight" with neck tension. According to Redding, .001 to .002 is OK, mainly neck tension just needs to keep the bullet from pulling during recoil. I would make a guess that the extra neck tension is allowing the primer/powder combe to burn more consistently. Not normally a problem in most loads?? /ubbthreads/images/graemlins/confused.gif
     
  5. Eaglet

    Eaglet Well-Known Member

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    Nice post, good shooting, thanks for sharing!
     
  6. Michael Eichele

    Michael Eichele Well-Known Member

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    Vic,

    [ QUOTE ]
    Can I ask how you adjust neck tension. I assume you are using the "S" type dies for which you can oder various neck tension dies.

    [/ QUOTE ]

    That is correct. I use the Redding S neck sizer with differant bushings. I neck size after using a body die to full length size my brass.
     
  7. Michael Eichele

    Michael Eichele Well-Known Member

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    Dave,

    [ QUOTE ]
    did you say you've repeated this a couple of times?

    [/ QUOTE ]

    Yes, many times with the same results. I dont know that the differance between .003 and .004" will make the same differance in every rifle, but at least in this one it does.
     
  8. jmden

    jmden Well-Known Member

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    Interesting post. Thank you.
     
  9. kraky

    kraky Well-Known Member

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    VERY INTERESTING!! By the way what caliber are you shooting. That RL data would seem real mild in a case that can hold 100 grain of bmg.....it must be an "accuracy load" you stumbled onto??
     
  10. Varmint Hunter

    Varmint Hunter Well-Known Member

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    I'd be curious to know what difference a further increase in neck tension would make.

    I've always used .002"-.003" and have never diaviated from this amount. There are too many variables to check in the endless search for precision and various neck tensions is just one I haven't experimented with yet.
     
  11. Michael Eichele

    Michael Eichele Well-Known Member

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    kraky,

    That is a very good observation you have there. It is a 300 RUM. The reason for the low RL-25 numbers is due to high pressures generated from the lack of case expansion because of the BR tight neck chamber in this rifle. With a 180 ACCUBOND, 90 grains yields a tad over 3300 FPS from a 27.25" tube. If I were to use normal data, I would have a bomb! This is the reason that I use H50BMG mostly. It is quite a bit slower than RL-25. I still dont get top velocities with it but I at least I can get a full case and I get 'good enough for me' velocities. 3200-3250 with the 178-180's with 100.0 grains and about 3125 with the 200 grain ACCUBOND at 96 grains. I really dont sacrifice much velocity using 50BMG and I eliminate one more variable by having a full case.
     
  12. Michael Eichele

    Michael Eichele Well-Known Member

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    [ QUOTE ]
    There are too many variables to check in the endless search for precision

    [/ QUOTE ]

    That is so very true. A guy could spend 10 hours a day experimenting with differant thing in the endless pursuit of perfection and he may never find all the answers.

    I too am curious if any more tension will improve accuracy or maybe even hurt it. I am ordering 2 more bushings and will report on those later.

    [ QUOTE ]
    and various neck tensions is just one I haven't experimented with yet.

    [/ QUOTE ]

    I may never have either. I stumbled on the idea when I didnt turn some necks correctly and ended up loading some with that dreaded donut inside the neck. I felt this when I seated the bullets. I thought awww what the heck, why not shoot em and see what happens as they all felt concistent during the seating proccess. When I shot them, accuracy at 300 was awesome. Obviously I could form an opinion based on one trip to the range so I bought the next size tighter bushing and tried it again. The results were the same. I have had the same results going back and forth over the last 10 or so trips to the range. Yesterday was the first time I had done a side by side comparison. Again, the results were the same.
     
  13. maggragg

    maggragg Active Member

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    Is this something that could make diffrence in factory riffle or do I need to have custom BR riffle to see diffrence?
     
  14. kraky

    kraky Well-Known Member

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    I had an interesting experience this fall. Was loading for a guys 7mm wsm browning autoloader. I got some hornaday dies and wow.....the case mouths were coming out at .276" opening. That's .008" grip. Bullets seated terribly hard and had lots of runnout. I thought....oh [censored]....my first job for my friend and these are gonna shoot really crappy.
    2 of the 4 test loads went to 3/4" and almost all of them went to the same point of impact. I was amazed. So was he.
    I contacted Hornady and they said that wsm brass necks are all over the place for thickness and that's why they are set up the way they are. Now we just withdraw the case over the expander,,,then raise it up over the expander.....and withdraw a couple of times while rotating the cases. That gives us .004" grip and good runnout. Now watch the accuracy go to hell?????!!!!! That's the fun of reloading....some of the stuff that slides together as smooth as butter shoots like crap.....then something that feels like you are virtually "hammering" it together shoots like a house of fire!!!!!!