Bullet runout what is the max?

Discussion in 'Reloading' started by Kaboom, Apr 16, 2012.

  1. Kaboom

    Kaboom Well-Known Member

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    Loaded up some .308 175 for a 600 F class (my second one) what do you feel is the range where runnout starts to be an issue? I figured .003 and above but that is just an uneducated guess on my part. Thanks in advance!!!!!:)
     
  2. boomtube

    boomtube Well-Known Member

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    How much runout matters depends entirely on the shooter, his rig and the other qualites of his reload. The throat a chartridge is seated into limits how much runout can exist in the chamber no matter what was was before chambering but that effect depends on the individual chamber and we don't know how well your ammo fits. The way a lot of us - and our rifles - shoot we will never see any effect with any amount of runout. Those of us who do see the effects of runout can't tell anyone else what their effect will be because it's not calibrated; if it were calibrated there would be a runout effect table in every reloading manual printed.
     

  3. rscott5028

    rscott5028 Well-Known Member

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    Some Palma shooters claim .5 and even .25 MOA to 600+ yds with up to .003" TIR for their loaded ammo.

    Some bench shooters won't accept less than .001" TIR and prefer .000".

    Like boomtube put it. There are a lot of variables that contribute to precision shooting.

    Try sorting your loaded rounds into best and worst and then shoot groups alternating shots between the good stuff at one dot and the bad stuff at another dot. Don't be too surprised if their accuracy is pretty close.

    In any case, consistency rarely hurts accuracy/precision.

    One thing I am very convinced of is that it's a complete waste of time to "straighten" ammo once loaded. Rather concentrate your efforts on loading straight ammo.

    -- richard
     
  4. Kaboom

    Kaboom Well-Known Member

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    Thanks Richard. I'm shooting a stock 700 Varmit gun so I kinda figured .003 as my cut off. Would this be a nonissue if I were to seat into the lands? I'm not but just wondering for future referance.
     
  5. Greyfox

    Greyfox Well-Known Member

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    I have done a lot of accuracy comparisons and found that seating depth/ distance from the lands seems to make a difference. The further from the lands, the less impact on group size. All that being said, I like to keep my run outs .003" or less. More seems to indicate a brass quality/reloading procedure issue. I have seen Federal premium factory ammo with run outs as far off as .010".
     
  6. rscott5028

    rscott5028 Well-Known Member

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    Ideal seating depth is an important part of load development.

    I don't think jump or jam seating overcomes excessive runout.

    Some situations may be more or less sensitive to runout.

    Like Greyfox indicated... if you seem to have excessive runout, then consider your brass quality, prep, and procedures. I like to start with good brass e.g. Lapua. But, people still shoot tiny groups with other brass.

    -- richard
     
  7. Kaboom

    Kaboom Well-Known Member

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    Thanks guys lots of good food for thought. That kinda confirmed my thought on seating in the lands. I understand it wouldn't cure the problem but might be less sensitive. I guess I should have also given more info on my load and process. bushing neck size to .338, then full lenght bushing size to .333 (no expander ball on either) seated with Forester noncrimp BR seater to 2.98 COL. 43.5 of Varget 210M primers Federal match brass neck turned to .013 wall.
    Barnes 175 match burners . Then check for runout on sinclair guage. I weight sort all brass & bullets. If anything throws a flag up here let me know, Thanks
     
  8. rscott5028

    rscott5028 Well-Known Member

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    I'm perhaps not be the best to comment. But, .013 seems like a heavy cut for Lapua brass. .015 would clean mine up nicely. I haven't measured Federal lately.

    If you're having to step down from ~.341 to .338 then .333, you may be working your brass more than necessary. I assume the two step sizing process is intended to help minimize runout?

    You may benefit from less turning, thicker brass, more frequent annealing, or a tighter chamber neck.

    Many feel that weight sorting brass is a distant second to measuring case volume. My limited experience is that there is little correlation between the two. But, I haven't concluded if either is worthwhile or which is better. So, I'm going to sort by volume for now.

    How do you like the Match Burners? Are they all copper? Do they foul much with long strings? I've had good results with the Berger 175 OTM. But, still too early to say for sure.

    ...take all that with a grain of salt. Perhaps someone with more competition experience will comment.

    Regardless, your actual results should tell you how you're doing.

    -- Richard
     
  9. Kaboom

    Kaboom Well-Known Member

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    The federal brass i started with had a .014-.015 neck wall. It was free and I'm just starting out so decided to make the best out of that. It's a stock chamber and fired brass measured .344. I'm basicly trying my hand with a stock gun with a jewel trigger & aftermarket stock, to see if I like the sport before I get a gun built and learn a little in the proccess. The Barnes shoot well in my gun 1:11 twist 1.5 @ 300. I did find that they need sorted as out of 200 rounds they were between 174.3-175.8. Most were 174.8-175.2, was a little concerned as being target bullets I thought they would be closer than that. Had maybe 25 that weren't in the 4.8-5.2 range. Haven't had any fouling yet but have only shot strings of 44-66.
     
  10. dieseldoc

    dieseldoc Well-Known Member

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    Run out does effect the performance of the shot that is out pass the 400 yard range,. Mine for my 6mmbr 105 gr Bergers have to be .0015 or less to shoot sub moa at 500 plus yards. With my 338edge run out have to be .002 or less to effective shoot past 600 plus yards with 300 gr Berger's.
    My seating is at .010 off the lands for both rifles. Only after using Redding comp dies have I been able to keep the run out under control.

    Interesting thing I did was to use my Hornady concentricity gauge and adjust the run out to .003-004-005 and .006.

    The results were , more the run out the loss of MOA on the target with everything being the same, power and charge, bullet and primer. Also the greater of run out the spread larger and did have a flyer every so offen
    For those that want to shoot under long range then I would don't worry about run out.

    charlie
     
  11. rscott5028

    rscott5028 Well-Known Member

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    I would bet that whatever your Hornady concentricity gauge registers is about half of your true TIR.

    i.e. .0015" is probably .003" TIR or greater when measure with a NECO or Sinclair

    I have the NECO and Hornady. And, that's been my experience.

    -- richard
     
  12. Bart B

    Bart B Well-Known Member

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    I think 30 caliber ammo with no more than 3 thousandths runout on the bullet tip is good enough as long as bullet jump to rifling is no more than a thousandth or so. Having tested ammo with such limits, some with full length sized and others with brand spankin' new unprepped cases, 1/2 MOA through 1000 yards is easy.

    Note that how the cartridge is supported makes a big difference in the amount of runout there is. Especially when there's no such thing as a perfectly round case body. Rimless bottleneck cases, when fired, center in the chamber's front end at its shoulder, not anywhere on the body. Any out of round condition of the body right behind the shoulder will be reflected in bullet runout if that point's one support location. It's better to support the front of the cartridge about mid point at its shoulder. It matters little where the back of the cartridge is supported.

    Note that smaller caliber in shorter cases can have about half the runout as larger caliber longer cases and both will have their bullets' axis at the same angle off the bore axis. The actual runout numbers are affected by the distance between the cartridge's resting points and the dial indicator's position on the bullet. It's easy for two different types of runout gages' setups to have a given round's numbers' twice as much on one compared to the other, which makes direct comparisons difficult.
     
  13. dieseldoc

    dieseldoc Well-Known Member

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    Richard:
    Cann't agree on gauges, as I have also Sinclair and it will be same as or not more than .0001 differance. Reason I use Horandy is to move a bullet if necessary.
    Charlie
     
  14. rscott5028

    rscott5028 Well-Known Member

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    Then, we agree to disagree on two points because bending case necks to reduce TIR is also a waste of time in my experience.

    But, I think people should stick with what works for them.

    respectfully,
    -- richard