Does concentricity matter ?

[JFrank]

Are they?

John's video says in his summary at ~5:45 that his results here with extreme run out with minimal influence downrange should dispell "the notion that you have to be at 1/2 a thousandths," and that these results "should help put a lot of minds at ease."

Bryan's video, even in his video description, states that his results show that "bullet run out up to 0.006" have no impact on precision." Which his Part 2 Video with bullets jumping also shows, and even runs the T test to show that the group sizes, though coincidentally different, are not statistically differentiated.

I didn’t actually watch his video, ( he and I don’t really see I to eye) I was going off of an assumption from previous engagement, if you get my meaning.
I stand corrected .. I did watch John’s though

 

[Varminterror]

Now that’s a quote for trimming 9mm brass...

Pretty much, that too!

 

[Theinkman]

My most used rifles are 2 x .22-250 and a .204 Ruger which get shot a lot on prairie dog trips. I have some very good loads for these rifles and have spent considerable time finding those loads. Still do a lot of testing as I love shooting these guns. When loading for these, I take a lot of measurements because I am a numbers guy and frequently those numbers tell me something interesting. What I seek when handloading, particularly these rifles, is consistency of process and components because I believe that is key in producing good ammo.

I don't neck turn my brass, because I don't want to. I don't check concentricity either because I don't know conclusively that it would make much of a difference. I am interested in reading about those things on this forum though as that gives me a chance to interact with shooters and handloaders much more knowledgeable than I.

But at age 66, I have been forced to accept that it is me that is the limiting factor when I pull the trigger.

 

[zeke]

Are they?

John's video says in his summary at ~5:45 that his results here with extreme run out with minimal influence downrange should dispel "the notion that you have to be at 1/2 a thousandths," and that these results "should help put a lot of minds at ease."

Bryan's video, even in his video description, states that his results show that "bullet run out up to 0.006" have no impact on precision." Which his Part 2 Video with bullets jumping also shows, and even runs the T test to show that the group sizes, though coincidentally different, are not statistically differentiated.

Bullet Runout Has Me Baffled

Hi guys, Have lately been having a bullet runout issue and can't figure it out,loaded rounds(400 or so)used to average .001"-.003" which I was fine with but now have been getting anywhere from .002"-.006"(and even at couple of .007").Specifics are 338LM,annealed with Amp MK II after every...

www.longrangeonly.com

Post # 15, bottom video, about 8:05

If this is Bryan's second video you are referring to when he redoes the test without jamming the bullet into the lands, and you actually watch the whole video, he determines that chambering the round with the .006 runout into his test rifle, that the runout is reduced to .0025 in by simply chambering the round (round with no primer/powder). When i see this, it appears to completely invalidate any conclusion that some reach by watching his first video. This video also strongly reinforces that what rifle being used matters, and it matters a lot. What is not clear is how much his rifle reduces runout when the bullet is jammed into the rifling. Gotta give the man credit for actually showing the results in the second video.

 

[GeoDudeFlorida]

It would be hard to prove that perfectly straight ammo will or will not out shoot ammo with say .003 run out, so unless it was done by someone I really respected as a world class rifle shot, I would take either results with a grain of salt.

Ever look at the "wailing wall" at a registered Benchrest match? (You know, where the targets are hung up and we go cry over the shots that got away).

If so, look at the wild variations in group sizes, even the best shooters group sizes go up and down. Now, try to be good enough to prove concentricity matters one way or another.

I think straight ammo is a good idea. I also like to take pride in my reloads. And, as already posted, it makes me all warm and fuzzy to know they are straight.

As has been posted, we test dies etc to make sure they don't load crooked ammo, whatever make, whatever it does to a case, we test it. We test it with concentricity gauges. Once we have a known good brass batch/good chamber/good sizer/good expander/good seater that loads straight ammo, we don't need to check much, but I still check a couple in each batch to make sure something hasn't gotten out of whack etc..

Plenty of better shooters than I waxing my butt at registered Benchrest matches who never checked concentricity, but hey, they were better shooters who shot more.

A pro pool shooter using a broom stick could beat my eyes out no matter what fancy stick I might have.

I saved these two targets, shot back to back same gun same shooter same day, I just let one get away on one target. Just a reminder on concentration and how important it is.
View attachment 1192078

I think this also demonstrates that it’s a nonissue except in the world of competition. Unless someone is shooting for prize money or bragging rights, it’s just not on their radar.

Checking old brass, especially for something like a Garand or a Ross rifle - where an OOB or torn rim can ruin more than just your day - for spring back and out of round heads makes perfect sense to me. But I don’t think I’ve met more than one or two people who did that. Most handloaders just trust their dies to give them straight cases and don’t worry about excessive wear until the case fails. IME.

 

[CQB45ACP]

I think this also demonstrates that it’s a nonissue except in the world of competition. Unless someone is shooting for prize money or bragging rights, it’s just not on their radar.

Checking old brass, especially for something like a Garand or a Ross rifle - where an OOB or torn rim can ruin more than just your day - for spring back and out of round heads makes perfect sense to me. But I don’t think I’ve met more than one or two people who did that. Most handloaders just trust their dies to give them straight cases and don’t worry about excessive wear until the case fails. IME.

So who is/was the pied piper of concentricity? The person that got this goat rope started? Made it popular enough to make it profitable enough for all the gauges to be produced and apparently sold? Are there really that many competitive rifle shooters?

I just searched on YouTube for concentricity and found 14 videos on the first search--likely there are more. I certainly didn't watch them all but believe only the February 16, 2023, video linked to by @JFrank asks the objective question "is it worth it". The rest appear to be, for lack of a better term, "how to" videos, presuming it's worth it.

Im not trying to take this off track and I know you all will ignore it if of no interest to you. I'm suspecting in a sense, group think or tyranny of the experts. Once a prominent "expert" says one thing, it's difficult for a less prominent or lesser expert to disagree. And the momentum builds.

Edit for clarification: it's the measuring I'm curious about, not concentricity per se.

 

[JFrank]

In quest of the perfect ammunition , one takes every step possible and leaves no stone unturned. As I posted earlier , if it instills confidence in one’s equipment then by all means continue with whatever practice.
Does it matter is a question only testing for oneself will answer.
Personally, I test a lot of dumb stuff just for my own knowledge and if I think it helps or have a quality tool for the job, I’ll continue and really don’t care what the other guy does or does not do.
For example I sort primers by weight, seat them to a specific depth, bullets three different ways, however after testing concentricity, I cant see any difference on paper at 500 yards so I no longer spend time on with it.

 

[CQB45ACP]

In quest of the perfect ammunition , one takes every step possible and leaves no stone unturned. As I posted earlier , if it instills confidence in one’s equipment then by all means continue with whatever practice.
Does it matter is a question only testing for oneself will answer.
Personally, I test a lot of dumb stuff just for my own knowledge and if I think it helps or have a quality tool for the job, I’ll continue and really don’t care what the other guy does or does not do.
For example I sort primers by weight, seat them to a specific depth, bullets three different ways, however after testing concentricity, I cant see any difference on paper at 500 yards so I no longer spend time on with it.

Yes I understand that overall point—it’s human nature—I certainly do it too.

And I incorrectly implied concentricity didn’t matter. I understand it does, but it’s how far one goes trying to measure it is the question.

 

[JFrank]

Yes I understand that overall point—it’s human nature—I certainly do it too.

And I incorrectly implied concentricity didn’t matter. I understand it does, but it’s how far one goes trying to measure it is the question.

good question..
I determined that for my program that it did not matter enough but all it takes is a good tool from 21st century or Accuracy one to check a few rounds to ensure your set up is making good ammunition within your personal standards. ( Hornday tool is awful and not worth any more then rolling a round on a mirror)

 

[buck460XVR]

Does concentricity matter ?​

IMHO.......yes and no. For most of us, probably not. But to those in competition where a tenth of an inch @ 100 yards means first or second, probably. Sometimes it comes down to what gives the shooter the most confidence. If the shooter believes it makes a difference, than odds are, his shooting will show evidence of it, whereas a stranger shooting the same ammo, with a different mindset, may not. I trim all my handgun brass I use for hunting for a consistent heavy crimp because I fell it helps me with accuracy at over 50 yards. Many here doubt that it does and don't bother. Many actually suggest it is a waste of time and I shouldn't either. But it's my time and my ammo, so I do what works for me. I suggest others do the same.

 

[zeke]

People spend big money on custom guns where concentricity is strived for , and achieved. Then more money is spent on tools that are designed to make their rounds as concentric (minimal runout) as possible, in addition to higher quality brass. Then they spend effort in perfecting their reloading process to minimise run out (concentricity).

After all this they consistently produce rounds with minimal run out, and use a rifle capable of correcting runout to minimal amount, they may decide to stop checking for "runout". They should be congratulated for their efforts. However to imply that concentricity (runout) doesn't matter will generate disagreement. To say there is no need to test for it is a very generalized statement that may apply to their specific situation after considerable expense and effort to achieve it.

While am not a competition shooter, first became aware of how runout can effect accuracy in a hunting rifle that produced 3 shot 1.5 in groups at 100 yds. After checking the factory rounds it was readily apparent some bullets had observable runout. Simply picking the rounds with non observable runout dropped the group size to 1 in, and the ones sorted out were used for bore fouling shots. Granted the rifle was a 257 wby with long free bore.

 

[Varminterror]

When i see this, it appears to completely invalidate any conclusion that some reach by watching his first video.

What is remarkable is that you can watch all of these videos and see that run out is proven to not matter, BECAUSE chambering the bent ammo into the rifle fixes the runout to within a standard which diminishes its influence on target, even to the point that you acknowledge and confirm that correction is happening, but then you dismiss everything you are seeing, simply for the fact you are seeing it…

It should be clear that the conclusion that the rifle fixes eccentric ammo is the driving hypothesis for the entire discussion. It is, and always has been.

 

[Walkalong]

To me, it’s like sleeved seaters, the straighter you start the bullet, the straighter it seats it, the sleeve can only do so much.

 

[lightman]

I'm one of those that thinks it does matter. In a factory hunting rifle you may not be able to see any difference. But in an accurate custom rifle I believe it does. My testing seems to show that somewhere around .004-.005 will show up in my groups. With my equipment and technique I usually see .001, maybe occasionally .002.

Like the others have said, good equipment and good technique will reduce your runout down to really small numbers.

Neck turning has been mentioned. I only neck turn for my rifles with tight neck chambers. My limited amount of testing had shown me that any improvements from neck turning are so small to not be worth the trouble in a factory chamber.

I'm not trying to change anyones beliefs, but I believe what I believe.

 

[zeke]

To me, it’s like sleeved seaters, the straighter you start the bullet, the straighter it seats it, the sleeve can only do so much.

Before i got to my current reloading process, used a Lyman mandrel for a smaller caliber cast bullet to help with bullet seating using standard seating die. It helped, but soon went to other methods/tools/bt bullets. There are fairly inexpensive methods to try in helping minimising runout. For years took a lot of flack on certain forums for not using an expanding plug (except when needed to use a certain case trimmer). Also took flack for the age old concept of squaring the body sizing surface of a die to the shell holder.

 

[Double Naught Spy]

But maybe the most important part of this discussion: Has anyone demonstrated the difference?

And if you could demonstrate a difference, would it be discernible from background noise? I see while making my response, Walkalong sort of hit upon this as well.

It would be hard to prove that perfectly straight ammo will or will not out shoot ammo with say .003 run out, so unless it was done by someone I really respected as a world class rifle shot, I would take either results with a grain of salt.

Even if it does, will it even matter to the 99.9% of shooters that aren't shooting competition? Would a 0.7" group be all that terrible compared to a 0.5" group at 200 yards for a deer rifle or self defense rifle? So even if it does make some sort of difference somebody somewhere might be able to discern, it doesn't sound like it is an issue for any but the uber elite of shooters.

 

[Varminterror]

To me, it’s like sleeved seaters, the straighter you start the bullet, the straighter it seats it, the sleeve can only do so much.

Ya' know, I wouldn't have necessarily referenced the link, but, I agree - and I carry a general internal conflict about sleeved seaters...

As a study of principle, I don't like sleeved seaters. Making two things straight is more difficult than making ONE thing straight. We say "stacking tolerances" about a lot of things, but in the case of sleeved seaters, we ignore the same phrase? In theory, we have more opportunity for movement, and SHOULD see more eccentricity in the ammo, and we SHOULD see that promote more dispersion in the groups...

BUT...

As a study of practice, I'll acknowledge that sleeved seaters do work to make small shooting ammo...

 

[CQB45ACP]

good question..
I determined that for my program that it did not matter enough but all it takes is a good tool from 21st century or Accuracy one to check a few rounds to ensure your set up is making good ammunition within your personal standards. ( Hornday tool is awful and not worth any more then rolling a round on a mirror)

I know for me, I’d have to measure the first time to verify/validate my processes were producing the best they could for my purposes.

Then, I’d measure the second time to compare to the first and ensure I was still on track.

Then…I’d probably buy a gauge to check again and as long as I already had a gauge, why not keep checking?

And yes, I know the real validation comes at the range, but one isn’t always at the range.

I say this only party in jest.

 

[Walkalong]

Ya' know, I wouldn't have necessarily referenced the link, but, I agree - and I carry a general internal conflict about sleeved seaters...

As a study of principle, I don't like sleeved seaters. Making two things straight is more difficult than making ONE thing straight. We say "stacking tolerances" about a lot of things, but in the case of sleeved seaters, we ignore the same phrase? In theory, we have more opportunity for movement, and SHOULD see more eccentricity in the ammo, and we SHOULD see that promote more dispersion in the groups...

BUT...

As a study of practice, I'll acknowledge that sleeved seaters do work to make small shooting ammo...

The old Lee “Dead Length” bullet seater uses the keep it simple philosophy. If the brass is straight, that die will seat straight ammo.

The die with no sleeve and a floating seater stem let the bullet follow the neck, so if your brass necks are straight inside, the loaded round will be straight.

 

[CQB45ACP]

The old Lee “Dead Length” bullet seater uses the keep it simple philosophy. If the brass is straight, that die will seat straight ammo.

The die with no sleeve and a floating seater stem let the bullet follow the neck, so if your brass necks are straight inside, the loaded round will be straight.

What is the "Dead Length" seater?

 

[westernrover]

It should be clear that the conclusion that the rifle fixes eccentric ammo is the driving hypothesis for the entire discussion. It is, and always has been.

So then a chamber would need to fix the eccentric ammo in order for runout not to matter. The evidence suggests that a very accurate rifle that likely has a chamber machined by a custom reamer corrects the eccentricity such that it is still very accurate when badly eccentric cartridges are fed.

Now suppose I have a factory Ruger rifle rather than a BAT custom. Does runout of the cartridges that I feed start to matter? My chamber might not be so tight that it fixes eccentric ammo, so does that mean I need to pay more attention to runout so the cartridge is concentric even in a relatively loose chamber? If so, to what degree can I benefit from controlling runout and by how much?

 

[Varminterror]

Now suppose I have a factory Ruger rifle

YOUR BARREL BORE IS STILL SMALLER THAN YOUR BULLET DIAMETER...

 

[Varminterror]

What is the "Dead Length" seater?

The Lee seating die which doesn't crimp - it may have been offered separately, but for years it was the seater they offered in their "Deluxe" 3 die or Collet Sizer sets. It ONLY seats, with no neck contact or crimping done. It was designed for the die body to always have contact with the shellholder, then let the dead-length seating stem be the only thing in the die touching the round. Nowhere to hide, ram travel or press flex couldn't throw off the reference length with these dies, as the distance between the shellholder and the stem can never change from one pull to the next, and the die can't induce any additional run out - like @Walkalong said, if the case neck is straight, there is nowhere else for the bullet to go but straight into the neck.

 

[CQB45ACP]

The Lee seating die which doesn't crimp - it may have been offered separately, but for years it was the seater they offered in their "Deluxe" 3 die or Collet Sizer sets. It ONLY seats, with no neck contact or crimping done. It was designed for the die body to always have contact with the shellholder, then let the dead-length seating stem be the only thing in the die touching the round. Nowhere to hide, ram travel or press flex couldn't throw off the reference length with these dies, as the distance between the shellholder and the stem can never change from one pull to the next, and the die can't induce any additional run out - like @Walkalong said, if the case neck is straight, there is nowhere else for the bullet to go but straight into the neck.

Thank you. I don't want to hijack thread but this is an interesting history lesson and begs questions such as why change?

 

[Varminterror]

Thank you. I don't want to hijack thread but this is an interesting history lesson and begs questions such as why change?

To my knowledge, they're still selling them.

They offer their Dead Length dies with their sets which include the Factory Crimp Dies and their Collet Neck Sizing dies because, as matters of philosophy, these alternative dies don't need or want for the seating die to also crimp the rounds. They offer their standard seating die with their 2 die sets because the set wouldn't otherwise offer any way to crimp, for those folks who want to crimp their rifle rounds (for whatever reason).