No-turn neck for 6PPC?

Discussion in 'Competition Forum (All Calibers)' started by chazgreen, Dec 19, 2008.

  1. chazgreen

    chazgreen

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    Thinking about having a new barrel made up with a no turn neck. In this site's 6ppc column, it mentions .271 & .272 as a possible nk size. Does this make sense? And does this mean that this is the actual size of the reamer? Lastly, would I then order a bushing for .270 for the .271 chamber? No, I doubt I would compete with the gun. As always, thanks/ Chaz
     
  2. fdshuster

    fdshuster

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    Charles: A second response to your 2 postings. Just measured the neck wall thickness on virgin Lapua 220 Russian cases, picked out of the box at random, using my tubing micrometer. Neck wall thicknesses vary from .014" to .015". Loading the rounds with brass as it comes "out-of-the-box", the whole purpose of loading for a no-turn neck, gives a total neck thickness of .030". Add to that the .243" bullet dia., and you get a loaded round neck dia. of .273". Yes, I also read the 6ppc info page & noted the recommendation of a .271"/.272" no-turn neck: just don't understand how that's possible, given the actual case neck thickness. Seems like a "safe" no-turn dia. would be .276? My present Heavy Shilen 1-14 has seen 1850 rds., so sometime in the near future will also be re-barreling and would consider a no-turn, rather than the present .262", so I have an interest in this whole subject. I'm not trying to start an argument, the people who put together the 6ppc info page are surely more knowledgable than I, but I would appreciate some clarification.:)
     
  3. chazgreen

    chazgreen

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    Thank you, thank you! I have yet to order 220 brass & have not even ordered dies, as I received this gently used rifle yesterday. Thus the questions about bushings, etc. The brass included with the rifle measures .2625 fired, .261 sized, and I seated a bullet using my 6BR die & got .2625. I deduce I need a .260 bushing. The issue about a new no-turn barrel with no-turn reamer & no-turn bushings is where I cannot figure given what I have on hand. I greatly appreciate everyone's advice./Newbee Chaz
     
  4. MarkS

    MarkS Silver $$ Contributor

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    Charles,

    I don't shoot a PPC. I would check with some of the reamer makes for sure on the neck.

    But I shoot IBS 600 yds benchrest, and most of the guys are shooting 6BR and 6BR imp's, shoot no turn necks. I shoot a 6BRX with a 0.271 and 0.272 neck. My loaded round is 0.2685 to 0.269", I use a 0.267" bushing.

    I hold the current LG group record 0.749". It will fall in Jan. when the pending record is scored. 0.711" also shot by a 6BRX 0.272' No turn neck.

    A No turn will work.

    Mark Schronce
     
  5. chazgreen

    chazgreen

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    Fdshuster/ your math makes sense to me; .030 brass plus .243 bullet equals about a .276 chamber diameter. I, also, would like to hear from the editors from the 6 PPC site about their recommendation of .272 for a no-turn neck. Hope they read this & respond. Thanks again/ Chaz
     
  6. fdshuster

    fdshuster

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    Charles: PM sent
     
  7. expiper

    expiper

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    one lil thing ...jst because the neck wall thikness is .015 as is....while they are still 220 Russian...doesnt mean they will be that thik when stretched out to 6mm...most un turned 220 Russian with all the dents and wrinkles ironed out are around .271 loaded and a .274 nk is a good no-turn dim....one thing most people forget,cause all we hear is 6mmBR.) is the thikness of 220 Russian is usually near what a .243 win,Lapua) finished dim is.....hope this helps...Roger
     
  8. fdshuster

    fdshuster

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    expiper: Your post got my attention. I briefly gave some thought to the "after expanding the neck" issue & disregarded it. Just now took a virgin Lapua 220 Russian, lot# 4PH5013) out of the box, again measured neck wall and got the .014" to .015". Pushed the shoulder back w/ a Redding FL die body, so it can be chambered in my 6ppc, then expanded w/ K&M expandiron mandrel. Cleaned the Imperial die wax off & measured neck thickeness: it remains at .014" min. to a few ten thousandths,.0003"?) under .015". So, using the .014" minimum, not what I'd do, "for real"), I still get a loaded neck dia. of .271", and you agree .274" would be a good no-turn dia.--- not the .271"/.272" as shown on the 6ppc info page. So, we are in closer agreement to the "safe" diameter, both of which are greater than the web-site dia. The difference between our "numbers" is .002": I'd just rather work with the larger,.002") "safer"? diameter of .276". I think we are in very close "disagreement" to the tune of .002".:)
     
  9. EdwinD

    EdwinD

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    I use a .274 reamer for a "no neck turn" PPC, AND it works flawlessly on my Lapua brass.

    A .272 will NOT work for me.
     
  10. fdshuster

    fdshuster

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    EdwinD: Thank you for the dimension/information, obviously from actual experience, not what we "think". I followed thru with the sample piece of Lapua brass & loaded w/ a 68 gr. Berger,, Wilson arbor press), and the outside neck dia. is .271": that plus .003" for clearance = .274". My .276" is probably a little in excess, so when I re-barrel mine, it will be with a .274" no-turn neck reamer. expipers .274" was right-on. Still waiting for an answer from the moderator as to how someone came up with .271"/.272" for a no-turn neck. That dimension would still require a light cut. Thanks again.
     
  11. expiper

    expiper

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    I am glad someone else has tried it....I have fooled with this stuff for all my life ...8ys now...,dog yrs..hahah)...one thing you havnt mentioned is FB!!! that is just as critical...If you are gonna use lil',60-75) bullets .020-.030 is just rite...but if your gonna shoot the big uns',105-107 etc.) thn .040 to .080 is better ....
    Im just guessin but I think the neck dia that was given in the article,blog) was a mis-strike out of habit for all the myraid of 6mm BR info given and used here....I know the moderator knows better..he is a competitor...and knows his "stuff" ...Roger
     
  12. EdwinD

    EdwinD

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    FB, "free bore", is like wine and women; it IS a matter of choice.
     
  13. Forum Boss

    Forum Boss Administrator

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    Folks,

    This discussion has been useful and we'll go back and measure some recent .220 Russian brass. In our past experience, neckwalls were running about .014, and that gets thinner as you expand the brass from .220 to .243 inside diameter, leaving about .027 added to .243 for a .270 loaded round.

    However, we just talked to Gene Beggs, who has played with a no-turn PPC and 6mm Beggs. He says the neck diameters of his loaded rounds made from current Lapua 220 Russian brass with a modern Flat-base bullet,with pressure ring) is .271".,Remember various 6mm bullets will display different true diameters--some are 'fat', while others are 'skinny). Gene recommends a minimum of .272" for a no-turn PPC, and he personally likes a .274" to give more clearance. He thinks having 0.0015" clearance per side may give better accuracy in a no-turn chamber.

    Accordingly, I am going to change the PPC article to dictate a .272" absolute minimum and a .274" recommended.
     
    BOB LEE SWAGGER likes this.
  14. chazgreen

    chazgreen

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    Gents/ thanks so much for helping a newbe reason through this muddle. I am happy to learn from you all./Chaz
     
  15. fdshuster

    fdshuster

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    Paul: A big Thank You for your response. Some would have blown it off/ insisted article was correct/ questioned the intelligence of anyone who had concerns about the "numbers"/ inferred they just fell off the turnip truck, or all of the above. This continues to be a First-Class site. Again, Thank You.
     
  16. chazgreen

    chazgreen

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    I'll second that. Thanks Paul/ Chaz
     
  17. Aussie_bob

    Aussie_bob

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    I have been reading this thread with interest as i have just bought a Stolle in Scoville stock My first dedicated benchrest Group rifle has 3 barrels all with .262" neck which means you are turning of a lot of brass so i am in the process of ordering my own reamers. I am going with a .270" neck which lets me clean up the necks for uniform thickness and still have plenty of wall thickness left which should give me uniform neck tension i will be useing 68gr projectiles would .030" FB be the norm.
     
  18. fdshuster

    fdshuster

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    Aussie bob: I like your thoughts. Had my first 6ppc built in 1998, and without knowing any better, let the 'smith use a .262" neck reamer/ that's what everybody was doing then, I've since been told. Now, I'm required to turn those nice thick .014" to .0145" necks all the way down to .085" to .009" Maximum to be "safe". When this barrel is "gone" it will be replaced with a tight no-turn, or your dimension requiring only a very light "dress-up" cut. As it is now, what a waste of high quality brass. I still cannot understand the reasoning for removing approx. .005" of thickness from the neck walls.
     
  19. mikecr

    mikecr

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    One reason IS consistant neck tension.

    Thinner necks provide very low and therfore very consistent tension. Afterall, a 10% variance in 10psi is much less than 10% of 60psi
    There is also less variance in springback, so sizing ends up more consistent from case to case to case.
    And there is some relief in straight seating FB bullets with truly concentric, light tension necks.

    I don't shoot BR. But I would be very surprised if a no turn, thick neck 6ppc, could shoot within the same zip code as the standards competing. I just don't picture corner cutting paying off.
     
  20. fdshuster

    fdshuster

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    mikecr: Best explanation I've ever heard: I've run the question by some "experts", 20 + yrs. experience), and all I get back is "gobiledegook": I don't think they even understood what they were saying. Your reasoning is very informative, for me, thank you.:)
     

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