Bullet Concentricity/Runout

[marchboom]

Of course, precision reloading is vital for the accuracy standard you have established but you may find the most significant variable is the shooter and environmental conditions.

I agree 100%. The equipment you bought is great but that's just part of the story. Make sure you have wind flags and a good, solid front and rear rest when you try out those loads. The wind alone could make your loads look like they are not accurate. Was the group size due to the loads or the wind?

Since you're spending money, a great book that explains a LOT about precision shooting is "The Book of Rifle Accuracy" by Tony Boyer.

 

[Straightshooter1]

I just saw this exact graph on a YouTube video last night. Is that your channel?

Nope.

But if I had one, it'd be a similar approach.

Interesting that I'm not seeing barrel quality on that graph
I would believe that a quality barrel holds more weight than cartridge selection
Only because I have seen what most would consider mediocre calibers
Shoot phenomenally when chambered in a custom barrel
a 223, 7 Mag, are just 2 calibers not considered particularly extremely accurate

I agree that barrel quality is a significant factor and thought that it should have been somewhere on that graph. But I think the emphasis was about cartridges and the reloading of them, were the more effective things done are in the reloading process. In the YouTube video series, it is mentioned that there are other things that can be done for improvement that are not on the graph, but are so small and best relegated to high end shooters where it's more likely to make a difference in competition and where winning is measured by .0001.

 

[CAS01]

What tools do you use to measure 0.0001?? (is 0.00254 mm) you need a climate controlled room at an even temperature and special tools and jig to measure these values. are the tools calibrated?
i don't believe you will see any difference at 300+ yards except for wind!!
just my thought (ex quality controller of sophisticated mechanical instruments)

 

[Bronsin]

Like you, a big part of the fun for precision reloading is seeing how well I can produce every aspect of it to as consistent as possible. Recently, I watched a YouTube video from Little Crow Gunworks channel that summed things up really well as the conclusions aligned very well with the things I've leaned since starting precision reloading. For example, here's a graph that outlines things in the order of importance for its contribution to precision:

View attachment 1655959

Primer seating depth and Neck Tension that low on the list? I'm suspicious of that.

 

[Straightshooter1]

Primer seating depth and Neck Tension that low on the list? I'm suspicious of that.

Which of those on that list would you say are less important than seating depth; or less important than neck tension?

 

[Bronsin]

Which of those on that list would you say are less important than seating depth; or less important than neck tension?

Primer selection and Component weight consistency. The primer is certainly important, but even the right one seated improperly won't shoot. If bullet and brass weight consistency isn't there, it's time to go shopping. It's a strange list. Some of the items are just a variable, whereas others are symptomatic of a tooling or process problem.

I would put the bullet first, along with it's seating depth. Then the powder and it's weight. Primer seating and neck tension are a dead-on tie. If either one is wrong, the load is wrecked. When I think about the accuracy of a load, I'm thinking about the adjustments to known good equipment, not how much or how little a different brand of brass will affect the load, or chamber pressure. Obviously it wont work without it, and practically every single item on that list affects it, so how do you isolate and place that one on the list?

Selecting the proper components and and having your tools and process sorted out eliminates half that list. That's just the way I see it.

 

[Straightshooter1]

I think you make some good points, but. . . I think you missed the point too???

For example, if you're advising someone who's brand new precision shooting (precision reloading being a big part of precision shooting), it about the order of magnitude for effect on precision for each these factors. A novice has a hard time taking it all in at once and often feel like they're trying to fill their drinking glass with a fire hose.

Primer selection and Component weight consistency. The primer is certainly important, but even the right one seated improperly won't shoot.

But, it you don't have the right one, seating it properly won't help. First you have to have the right one. Seating a very wrong one properly isn't going to help much, huh? And if one is getting no better than 3/4 MOA, I don't thing any improvement with this primer issue is going to show up???

If bullet and brass weight consistency isn't there, it's time to go shopping.

I assume you're pulling that out as a subset of Component Weight Consistency, though "brass weight consistency" is probably more the subset of Brass Quality.

It's a strange list. Some of the items are just a variable, whereas others are symptomatic of a tooling or process problem.

Hmmm??? "Just a variable" or a "tooling process problem", they all a pretty key points to give attention to and pretty much in that order, IMHO.

I would put the bullet first, along with it's seating depth. Then the powder and it's weight. Primer seating and neck tension are a dead-on tie. If either one is wrong, the load is wrecked.

I do understand what you're saying. This presumes a cartridge selection has already been made, huh? I'm sure with your experience, you know that some cartridges just don't do well or as well as other cartridges in terms of precision shooting results. If a poor cartridge is selected, none of that that follows is really going to help a whole lot (like consistently shooting 1/2 MOA groups that's often one's goal).

When I think about the accuracy of a load, I'm thinking about the adjustments to known good equipment, not how much or how little a different brand of brass will affect the load, or chamber pressure. Obviously it wont work without it, and practically every single item on that list affects it, so how do you isolate and place that one on the list?

It's about taking steps where to focus before the next thing. Very often we see in this forum and other forums where advice is given long before the novice has really addressed more important things.

Selecting the proper components and and having your tools and process sorted out eliminates half that list. That's just the way I see it.

Yes. . .agreed! Though, all that takes a learning curve over time. . .and why so many of us have tools, even processes, that we don't use any more.

BTW: Thanks for your response, appreciate it.

 

[r bose]

Hi all, I upgraded my whole reloading setup recently and just got everything set up. Using an Amp Annealer, Amp Arbor Press, Short Action Customs Infinity in-line Seating Die, Area 419 Zero Gen II press (for sizing), Area 419 M series FL sizing dies, Accuracy One Concentricity gauge, and Henderson Trimmer.

I'm trying to squeeze every little bit of accuracy out of my rounds. I know all this isn't necessary, but it's my hobby and I enjoy trying to chase every minuscule imperfection.

I recently loaded up some new cases (Peterson) and am not thrilled with the bullet Concentricity. I got anything from 0.001" to 0.004" on my bullet Concentricity. I anneal, full length size, trim and then seat using the arbor press and in-line seating die. For 6.5PRC I'm using the standard SAC neck guide with the M2 seating sleeve as recommended from SAC.

I believe my process is pretty dialed in, but the only thing I can think about is whether the fact I'm compressing powder for these rounds is making me get slight variations in runout? I've also measured my neck Concentricity and am getting .0005" runout on the neck, which should be great.

Appreciate any help!

I'd make sure the "cone" in the seating die is contacting the projectile when you're seating the bullet. Bullets have become so pointy, it's possible for the tip will touch the top of the cone first giving poor runout. When seating, look for the slight ring around the projectile where the cone is contacting it.

 

[GetReal]

I do mostly all the same stuff with the same gear except I use l.E wilson seating dies and get run out of 0.0005"

 

[GetReal]

I also recently learned that too tight a neck with more than 0.003" neck tension Can cause the case neck to crush and be distorted.

E.g. Seating a 0.308 bullet in a 0.298 neck.

 

[padom]

There is nothing “straight” about most out of the box factory cases.
Fireform them, do your usual sizing operations and see if things improve.

This...

Most die companies tell you to measure runout on once fired in your chamber and sized brass. Virgin brass has runout and should be ignored...

 

[G Liles]

The only time I worry about runout is when I don’t load enough ammo, because if you don’t load enough you will runout!!

 

[6BRA]

If you don't turn necks, don't waste your time with a concentricity guage.You will never get rid of .0015 runout due to brass high side and low side.
If you do turn necks, A 5 decimal ball mic and a concentricity guage may tell you how well you turn your necks on fireformed brass. My experience not all devices and people turn necks to the exact tolerance across 50 pcs of brass. Neck turning is a science to achieve exact specs across 50 pcs. Not as simple as it sounds. And some devices work better at it. How critical is it to have exact neck tension? For groups and score, it will show on paper. When someone says they shoot .25 moa. I think well at 100 that's easy. At 200 that's not incredibly hard. At 300 and beyond I question anyone to do it consistently. If you can, your name should be at the top of every shoot in the country.

 

[Gary C]

I'm not extert by any means.
I have found by real life range time that my rifle likes the bullet seated
.010 into the rifling.
I tried jumping and never got the results that the .010 in gave me with both of the barrels that I have used.
Logic tells me if there was any run out before the round is in the chamber it should be gone when the bullet
enters the rifling.
Yes,No?

 

[One Eye Pete]

The one thing I have never worried about is bullet concentricity. I normally use a good quality bushing type full length sizing die (Redding, Whidden, Harrells, Cortina, Forster ect.) a Sinclair mandrel die and a LE Wilson straight line micrometer seating die. I don't bother to measure my bullet concentricity because it is generally good and it doesn't matter all that much to my on target accuracy. What I am fanatical with is bullet seating depth. For my match ammo my BTO is normally +/- 0.0005. I have found bullet seating depth to make a big difference.
You stated above that you are using a compressed load. This can have a bad effect on bullet seating depth. If you don't believe me check out Tony Boyers book. With compressed loads bullets can move out of the case over time.
In my pursuit of accuracy I haven't gone the route of more expensive reloading equipment but rather measuring and sorting components. For long range shooting sorting bullets by overall length and pointing them has helped. Sorting primers by weight has helped reduce flyers. (when weighing primers every once in a while you get one that is either very heavy or very light, which can equate to a flyer).
In the end the only measurement that actually counts is where the bullets land on the target.