NECK RUNOUT
- Thread starter AL PALMER
- Start date
condor bravo
New member
Consider .000 to .0015 to be excellent; .002 to .003.5 to be good; .004 to .0055 to be average; and much beyond .006 or higher to be excessive. These figures might be a little on the high side but are ball park. The challenge is to get all cases good or better.
Condor and Dufus nailed it in regards to your question but here is a article on runout and accuracy.
https://rifleshooter.com/2016/02/rifle-cartridge-concentricity-and-accuracy/
it tries to show that even 2 MOA ammo shoots better with less runout. Draw you own conclusions as to what if anything his test showed. I would love to see that test performed by a good shooter with a accurate rifle who could figure a way to tweak the runout accurately
edit- On correcting runout the only gage I have used is the Hornady and it has a screw that you can use to put pressure the bullet and try and force it into alignment. Best thing to do though is make sure your neck stays concentric in the sizing operation. I use either a Lee Collet or a Redding S bushing FL with the expander ball removed
https://rifleshooter.com/2016/02/rifle-cartridge-concentricity-and-accuracy/
it tries to show that even 2 MOA ammo shoots better with less runout. Draw you own conclusions as to what if anything his test showed. I would love to see that test performed by a good shooter with a accurate rifle who could figure a way to tweak the runout accurately
edit- On correcting runout the only gage I have used is the Hornady and it has a screw that you can use to put pressure the bullet and try and force it into alignment. Best thing to do though is make sure your neck stays concentric in the sizing operation. I use either a Lee Collet or a Redding S bushing FL with the expander ball removed
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I looked into it and unless its wild and or you shoot 1/10 inch groups, it seems to not be a factor and its touted now to sell more tools.
As HoundDawg notes, what we lack is scientific tests and data to show what really works and what is worth while working to at any given level of shooting (hunting makes not different, they used to shoot Buffalo with arrows for crying out loud) Louis and Clark shot their way across the Western US with an Airgun (some of their grizzly shoots are literally hair raising though I think that was with Kentucky type ball rifles, who needs a 415 Rigby really?
As HoundDawg notes, what we lack is scientific tests and data to show what really works and what is worth while working to at any given level of shooting (hunting makes not different, they used to shoot Buffalo with arrows for crying out loud) Louis and Clark shot their way across the Western US with an Airgun (some of their grizzly shoots are literally hair raising though I think that was with Kentucky type ball rifles, who needs a 415 Rigby really?
Went down that road , Redding S Type bushing dies, Hornady concentricity tool , carbide expander expander ball . It's best to have ever reload exact so you can eliminate the round an then put the blame on barrel ,bedding , scope , rings , screws , trigger , wind and last me . I don't neck turn my brass , I use the expander ball , tried it without letting bullet seating do the expanding . Runout with the bushing dies were much higher .
Went back to the standard RCBS F/L die , worked much better , average .001 runout . I even removed the ejector plunger spring with a very light spring so plunger is flush with bolt face . Thinking plunger was putting uneven pressure on the case base when chambered , Rem 700 . Found over thinking was the problem . I now stick with the same accurate load an concentrate on my form . My groups are consistent good , for me . A flyer I know is caused by me , nothing else , I can call a flier , doesn't bother me . I enjoy benchrest shooting much much better now . Could be even 3 much's.
To turn things upside down now , I've read articles that bullet concentricity does matter when shooting long range . I'm shooting 200 yards maximum 1/2" groups for me and I'm happy.
Went back to the standard RCBS F/L die , worked much better , average .001 runout . I even removed the ejector plunger spring with a very light spring so plunger is flush with bolt face . Thinking plunger was putting uneven pressure on the case base when chambered , Rem 700 . Found over thinking was the problem . I now stick with the same accurate load an concentrate on my form . My groups are consistent good , for me . A flyer I know is caused by me , nothing else , I can call a flier , doesn't bother me . I enjoy benchrest shooting much much better now . Could be even 3 much's.
To turn things upside down now , I've read articles that bullet concentricity does matter when shooting long range . I'm shooting 200 yards maximum 1/2" groups for me and I'm happy.
We'll see what Al Palmer is actually interested in knowing. If it is neck wall runout, I see around 0.0025" TIR as pretty typical. I've had Norma and Lapua that were all 0.001" or less. I've got a fifteen-year-old lot of Winchester .308 brass that averaged about 0.003", with one single case that was 0.008" in wall thickness runout. Since this number typically is reflected in the overall bullet runout and centering failure in the chamber, I don't like to see anything over 0.001" for precision loads and will use outside neck turning if I can't select enough from a lot for my precision loads that came out like that by happy accident.
If he is talking about neck tilt or OD runout on a resized case, as caused typically by expander pull, I've seen long necks on .222 Rem and .30-06 give me numbers as high as 0.002" on my Co-ax press, but that's about it.
If he is talking about assembled cartridge runout, I've seen up to about 0.010" loading by hand. The author of that article found worse. But the better article, if you get a copy, is A.A. Abbatiello's article in the old NRA Handloading book (p.87). He got samples of 42 lots of .30-06 National Match ammunition and measured runout and had good shots fire them in match rifles and got some hard data to show about 0.004" of tilt off-axis, as measured with the back and tip of the bullet centered and runout taken from wobble at the bullet just in front of the case mouth, would open groups about 1 moa. He also showed that number or half a thousandth more is roughly the limit of the effect. Any more tilt than that was straightened out by the bullet entering the rifling. He showed a center of mass error calculation that predicts the effect and he found that if you find the high side of your rounds and load so the high side is at the same side of the chamber, it cuts the error contribution on the target in half.
Harold Vaughn (the price at the end of that link is rediculous) repeated the experiment with a different bullet in 6 mm out of a super-precision integral machine rest gun firing through 100 yards of sewer pipe to eliminate wind, confirming the theory, but the different bullet shape didn't allow nearly as much tilt to remain in the barrel (longer number of calibers of bearing surface, so the bore straightened out more of the tilt; the old M1 Type bullet in National Match ammunition only has a 0.88 caliber bearing surface). His result was a little less than half the group opening effect that Abbatiello got. But he also did a noteworthy thing to test it that the OP or anyone here could try. He took eight cartridges with the maximum tilt and marked the high point of the runout and then fired, loading each successive round 90° clockwise in the chamber from the previous one. The result was a 4-leaf clover group, with two holes making up each leaf, thus establishing both Abbatiello's observation that where the bullet starts in the chamber controls the direction of the drift caused by the center of mass dislocation off the bore axis, and finding the diameter of the group error they imposed.
Below is a drawing I took off Vaughn's information and how it would look if Abbatiello had done the same thing based on his measurements. You can see it makes quite a difference what bullet you are using (Vaughn's was a stubby ogive flat-base benchrest bullet, while Abbatiello's was a longer ogive bullet with an extremely long boattail).
If he is talking about neck tilt or OD runout on a resized case, as caused typically by expander pull, I've seen long necks on .222 Rem and .30-06 give me numbers as high as 0.002" on my Co-ax press, but that's about it.
If he is talking about assembled cartridge runout, I've seen up to about 0.010" loading by hand. The author of that article found worse. But the better article, if you get a copy, is A.A. Abbatiello's article in the old NRA Handloading book (p.87). He got samples of 42 lots of .30-06 National Match ammunition and measured runout and had good shots fire them in match rifles and got some hard data to show about 0.004" of tilt off-axis, as measured with the back and tip of the bullet centered and runout taken from wobble at the bullet just in front of the case mouth, would open groups about 1 moa. He also showed that number or half a thousandth more is roughly the limit of the effect. Any more tilt than that was straightened out by the bullet entering the rifling. He showed a center of mass error calculation that predicts the effect and he found that if you find the high side of your rounds and load so the high side is at the same side of the chamber, it cuts the error contribution on the target in half.
Harold Vaughn (the price at the end of that link is rediculous) repeated the experiment with a different bullet in 6 mm out of a super-precision integral machine rest gun firing through 100 yards of sewer pipe to eliminate wind, confirming the theory, but the different bullet shape didn't allow nearly as much tilt to remain in the barrel (longer number of calibers of bearing surface, so the bore straightened out more of the tilt; the old M1 Type bullet in National Match ammunition only has a 0.88 caliber bearing surface). His result was a little less than half the group opening effect that Abbatiello got. But he also did a noteworthy thing to test it that the OP or anyone here could try. He took eight cartridges with the maximum tilt and marked the high point of the runout and then fired, loading each successive round 90° clockwise in the chamber from the previous one. The result was a 4-leaf clover group, with two holes making up each leaf, thus establishing both Abbatiello's observation that where the bullet starts in the chamber controls the direction of the drift caused by the center of mass dislocation off the bore axis, and finding the diameter of the group error they imposed.
Below is a drawing I took off Vaughn's information and how it would look if Abbatiello had done the same thing based on his measurements. You can see it makes quite a difference what bullet you are using (Vaughn's was a stubby ogive flat-base benchrest bullet, while Abbatiello's was a longer ogive bullet with an extremely long boattail).
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condor bravo
New member
Note to Al Palmer:
There can be a large difference between runout of a resized empty case and bullet seated runout of a loaded round. For example runout of a resized case may be .001 but bullet runout of a loaded round might be .005. To check the difference, measure runout on the seated bullet just forward of the case neck. This measurement will be of more importance than just case neck runout without seated bullet.
There can be a large difference between runout of a resized empty case and bullet seated runout of a loaded round. For example runout of a resized case may be .001 but bullet runout of a loaded round might be .005. To check the difference, measure runout on the seated bullet just forward of the case neck. This measurement will be of more importance than just case neck runout without seated bullet.
I did. His conclusion was inconclusive as he had irregular ammo.
Please repeat the test, but this time use the same case (weight and capacity) as well as bullet (weighed and checked for balance) same primer (tested to have the same oomph - but you only know the last oompth, the next oomph could be way off ) and then move the bullet off concentric .
Do it inside a warehouse that has a controlled temp and humidity.
It will be an interesting test.