lapua brass prep

Discussion in 'Reloading' started by Frogman77, Feb 23, 2010.

  1. Frogman77

    Frogman77 Well-Known Member

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    Do I need to uniform primer pockets, flash hole deburr, and neck turn lapua brass??

    I know it will probably be minimal but I don't mind doing case prep if it will help.

    thanks in advance!
     
  2. Winchester 69

    Winchester 69 Well-Known Member

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    Nope.

    Make sure the neck is round, and then chamfer. Trim to uniform length after firing. Re-chamfer as needed.

    Neck turning is performed to fit the case neck to a custom chamber. You can check for variance in case neck thickness if you wish using a ball mic. Simply cull any really bad cases, if you find any.

    Uniforming the primer pocket assures 100% reliability by providing a flat seating surface for the primer's anvil. There is no influence on accuracy.

    Benchresters will tell that flash hole de-burring has a huge influence on their accuracy. Will your gun realize it? Prepping that area started as a means for removing large flash from around the hole that would obstruct flame propagation. Lapua brass doesn't have any flash of that proportion. If you have the tool, you can A/B some cases and decide for yourself what benefit is to be realized. I use a large twist drill (by hand) on my non-premium brass to knock off any burrs.

    Just using the premium brass averts many ills.
     
    Last edited: Feb 23, 2010

  3. Mikecr

    Mikecr Well-Known Member

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    This is the best thing you can do for this brass.
    For thickness variance, depending on cartridge & lot, I have seen Lapua worse than other brands.
    The best I've seen, believe it or not, is Winchester's reloading 25WSSM brass.
    The worst I've seen, was Lazeroni scramjet, Tubb 6XC, one very ugly Norma 223 case, and a single lot of Lapua 6br brass. But other lot's I use are very good.
    I don't assume anything with brass.
     
  4. phorwath

    phorwath Well-Known Member

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    I still like to uniform primer pockets on Lapua brass. It helps me seat the primers more uniformly by feel - compared to non-uniformed primer pockets.

    I have trouble telling when I've bottomed out on the non-uniformed Lapua primer pockets.
     
    Last edited: Feb 23, 2010
  5. Frogman77

    Frogman77 Well-Known Member

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    The necks I've measured vary from .0135" to .0152" or so. Most measure between .014 to .015". I was thinking about maybe just cleaning up the necks to .014 to .0145".

    Do you think it's even worth the trouble?? I guess only one way to find out...

    What would be considered worth turning the necks? how much variance in thickness?
     
  6. Mikecr

    Mikecr Well-Known Member

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    It's a tough question Frog..
    What cartridge?
    What use?
    What kind of chamber?
    Do you have the resources to pickup alot of brass?
    How important to you is really straight ammo?

    I ask because a 1/2moa potential hunting gun from a SAAMI chamber, with factory dies, might not reward turning/culling efforts compared to other areas of focus. Especially if your bogged down with many guns to reload for.
    Afterall, you hesitate to take on this turning load,, to go for pure perfection, for it's sake.
    And that flags me that you don't want to 'waste' any efforts.

    Will cleaning up the necks directly improve the gun's performance?
    No.
    Turning is done to produce lower tension -consistantly, and to reduce runout. This can reduce ES, and eek out possibly 1/10th better short range grouping. Maybe 1/4 better LR grouping.
    It will do nothing for accuracy, without diligent combinations that benefit from it(like a camshaft in an engine).

    But if this gun is your main project,, your immediate passion,, hell yea make perfect ammo and get the most from it..
     
  7. Frogman77

    Frogman77 Well-Known Member

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    It's a .30-06 built for precision and long range out to 1000m/ I know odd cartridge, but it will give me a longer barrel life than some of the bigger magnums...and yes, right now it is my main project..

    in anycase with win brass fully prepped, I can get 1/2moa with quite a few sub 1/4moa groups...but I still get flyers in a 10 shot string...most likely shooter error, but I want to minimize all the variables.

    the win brass i had to turn the necks down to .012" but they were thinner necks to begin with...the lapua is thicker and they were more consistant to begin with...

    I definitely want the straightest ammo possible with out damaging the brass quality if that makes sense. That being said, is it more beneficial to "clean up" the necks 80% turn or should I turn them so that they're even all around?

    chamber is min spec SAAMI.
     
  8. Gene

    Gene Well-Known Member

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    My Lapua brass purchases are limited to .223, 6PPC, and 6BR. I used to do all that "feel good" stuff. But I no longer uniform inside flash holes, nor primer pockets. Lapua brass is so good, that it is not necessary. New brass gets trimmed, champfered, and necks expanded. If it is for a tight neck chamber, I turn the necks. With Remington and W-W brass, the flash holes and primer pockets always need to be cleaned up.

    By all means, do everything possible if it will give you more confidence in your loads.
     
  9. tlk

    tlk Well-Known Member

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    Frogman, sounds like we have nearly and identical setup. I too have the 30-06 for distance shooting and also have sub-1/2" groups. But I also am seeing the same thing with my Lapua brass. WW and Rem is much worse when it comes to brass variation.

    I came here today to post a question about this exact thing, so here goes: I have a forster comp seater die. There is no bushing for it. My case necks are in the .0125 - .0155 range previously noted in this thread, and I would like to clean this up. How do I tell how much grip my dies would be putting on the bullet if I uniform the neck (outside turn)? Do I call it .0135 - .014 like was mentioned or am I just making it all worse because the die wont seat properly because of the missing brass(i.e., not using the right seating die)? This sounds wrong because I have seated in necks turned to .0125 without any issues, but I dont really think I know what I am doing to be honest.

    Any help with this would be greatly appreciated.
     
  10. Mikecr

    Mikecr Well-Known Member

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    Why would a seater die have a neck bushing?

    I don't use Forster, but if NECK thickness effects it's operation, I suggest you promptly drop it in a trash can & get a better seating die.

    Seater dies do not grip bullets.
     
  11. tlk

    tlk Well-Known Member

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    You are correct! I am today's "working moron":D. Please forgive the non-caffeinated rant. Did I really write that? Oh well, can't take it back now since you quoted it - preserved for the ages!

    What I meant to say was this: will using a standard sizing die cause an issue with the neck tension on brass that has been turned to .0135-.014? The reason I ask is that I am using a Lee Collet, and have been advised that neck turning while using a standard (non-bushing) die does little that is advantageous because the neck tension cannot be controlled. The idea being that repeatable neck tension is a function of both consistent neck thickness AND a bushing-type die.

    It would seem that neck tension can NEVER be controlled on new (unturned) brass straight out the bag due to the thickness variations from neck to neck, regardless of the dies that are used. Therefore, it would follow that the only way to get consistent tension is to create a consistent neck via turning and then setting your dies the same every time (regardless of what flavor it is). Basically neck turning becomes a journey to establish a known constant (one thickness) from a series of fixable variables (multiple neck thicknesses). I can live with that, if the explanation is that easy. But it also means that 80% trued is 20% off - knocking off the high spots only reduces the variability, it does not eliminate it - consistent neck tension may not be obtained and flyers could still result.

    But how come non-bushing sizing dies are not optimal if all necks are turned to the same thickness? What aspects of neck tension are the sizing dies with bushings controlling that the other dies are not if the neck are the same?
     
    Last edited: Feb 25, 2010
  12. Mikecr

    Mikecr Well-Known Member

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    Desired tension is produced by adjusting neck sizing among other things, and bushing dies are adjustable for this. FL dies which size necks are not adjustable, and so may need to be customized to properly account for your brass.
    Combine this with the fact that there is nothing good in sizing the entire neck, and a strong basis for bushing dies comes to light..

    But don't confuse thickness variance from case to case, with variance 360deg around each.
    Tension through sizing is influenced by overall thickness produced springback.
    Loaded runout is influenced by 360deg thickness variance. This doesn't affect tension.

    Turning necks does bring both to an improved standard.
    But like any improvement, it takes a plan/further actions to see it's gain.
    In the case of turned brass, you need to consider your chamber and dies.
    You need to have a plan.
     
  13. tlk

    tlk Well-Known Member

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    Mike, can you explain what the plan would be? Not trying to be hard to deal with, I just dont get what you mean.
     
  14. Mikecr

    Mikecr Well-Known Member

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    I had a Browning A-Bolt rebarreled to 6br Norma.
    This was a case where I didn't design & hold the reamer. I let the gunsmith use his given that it's enough challenge just to rebarrel a Browning(extended tennon, epoxied, interference fit). This was J.Kolbe, and he did an incredible job on the chamber, fit & finish.
    Anyway, Jim says it's a bit tight.
    So I turn a culled case neck to an even .013" thickness, seat a bullet and try chambering(it failed to do so). I turn another to .0125" thick and find that it chambers ok.
    So..
    No-Go case = .269 NK(.013 thick, x2, +.243)[Chamber Neck]
    Go case = .268 NK(.0125 thick)
    For 1.5thou total clearance, I need to take necks to .0115" thick(.2665 loaded neck).

    For 1thou of tension on .2665 necks, I need a .265 bushing, which accounts for .0005 of springback on my sizing. .2665-.265= .0015-.0005= .001 tension.
    For reloading, I'll be using standard Wilson dies on this one.
    I pickup a Redding titanium nitrided bushing in .265 and drop it in the neck die.

    I use Lapua brass in 6br & I have a bunch. I picked out 200cases with low thickness variance(360deg). Of these the brass measured ~13.5thou thick, so it's an easy turn.
    After fire-forming I lost only 7cases to H20 capacity differences.
    That leaves me 193 diamonds. Plenty enough.

    After a few firings, I sent several cases & a Redding body die to JLC Precision for minimal sizing/bumping.
    This chamber & system has produced the lowest loaded round TIR that I have ever measured. It's low 10thous and prepolishing is required to see runout over surface noise.

    This was a basic plan, far easier than required for a wildcat.
    You can scratch it out on paper before ever beginning, but to do so you need all the brass your going to use for a barrel -in hand, so that you can measure it.
    Similar plans are needed for a gun build from scratch, and this all begins with a bullet.