Bullet runout or concentricity

[Dave M.]

They are both under .0005. I'll find a holder for my phone to film. That needle is barely moving. Those rounds have .004 neck tension. I am also jumping the wheel because I am only using 1 finger. I normally run the wheel between my index and thumb.

Don’t sweat it, I was merely busting your balls. I just went down and took a picture of my accuracy one gauge….take a look how much dust was on it. Before and after shot

 

[gdbleb]

Dust covers for concentricity gauges. New business opportunity. I know I need 2.

 

[6BRA]

I have tested this a few times. I know other guys that have as well. The funny thing is how similar the results are. The typical answer is they were so close it was a wash but the crooked rounds actually shot a little smaller.... now why is that?

Don't let me get a hold of your stuff at the Tack Driver. We will find out....LOL

 

[Idaho-Lefty]

Your runout more than likely isn't your seater. More than likely your sizing process. Unturned brass could add .0015 to your runout alone on case neck.

I Use ONLY, Forster Sizer's, in almost All of, my Reloading Die Sets, now !
Even Bought, a Few Used ones,. off, E-Bay !
Just learn HOW / Where, to adjust, the Expander Button and your,.. "Good to Go" !
I Always Get,. .000 to, .002 TIR, Max. run-out ( I check the TIR, before making, a Run of, 50 Cart's )

 

[Webster]

I have tested this a few times. I know other guys that have as well. The funny thing is how similar the results are. The typical answer is they were so close it was a wash but the crooked rounds actually shot a little smaller.... now why is that?

Maybe the group size was influenced by some unknown other than what you were testing for. Many things going on and assuming the results were related to what you wanted them to be.

 

[quest450]

Fired case runout

Sized case runout

Loaded case runout

 

[DShortt]

Fired case runout

Sized case runout

Loaded case runout

OK. So your fired case run-out is .001"
Your sized case run-out is .001"
Your loaded case run-out is .0005.

That's all well and good.

How many rounds down the bore?

What is the group dispersion?

Is this the same case?

Is this repeatable?

These videos leave me with questions but few answers. If I missed a prior post that answers these questions, please point it out. I thought I read the thread thoroughly, but I may have missed it. I am genuinely curious regarding the experience of others.

Thank you.

 

[quest450]

all valid questions SIR

fairly new-ish barrel 194 rounds

I was testing a load this past weekend and wasn't impressed 2.827" agg 4th place in our Freedom Benchrest 600yd Match

not the same case just randomly picked cases

repeatable.....I think so, honestly I never care about the runout.....paper tells me all i need to know

I just picked a few cases out of my box to check the runout and contribute info to this thread with a video being worth a 1`K words.

 

[6BRA]

all valid questions SIR

fairly new-ish barrel 194 rounds

I was testing a load this past weekend and wasn't impressed 2.827" agg 4th place in our Freedom Benchrest 600yd Match

not the same case just randomly picked cases

repeatable.....I think so, honestly I never care about the runout.....paper tells me all i need to know

I just picked a few cases out of my box to check the runout and contribute info to this thread with a video being worth a 1`K words.

Were necks turned? Thats .0015 runout if they werent.

 

[quest450]

Were necks turned? Thats .0015 runout if they werent.

Yes, AUTODOD turned, my brass has less than .001" runout after fireforming.......... I think my gunsmith and my reamer are responsible

 

[Bc'z]

I would like to hear more about the press inducing runout. Care to share more details?

Dirty shell holder will induce run out, I try and clen groove every loading session.

 

[DShortt]

So, in previous posts in this thread, I've noted that at it's been noticed that run-out isn't a problem.

What I've not noticed is, has anyone tried checking run-out on a 'shot out' barrel?

Perhaps it's not significant when the throat is new and more significant if it's worn or, perhaps 'generous' to begin with?

I'm just asking as someone might have tested this before. Actually, I'll be surprised if someone hasn't tested this before. I'd dearly love to hear what they documented.

 

[Dave M.]

Maybe the group size was influenced by some unknown other than what you were testing for. Many things going on and assuming the results were related to what you wanted them to be.

Or that neck TIR is merely noise when you measure the rounds with no TIR vs the rounds with 1.5-4.0 thou of TIR.
Dave

 

[Dog Hammer]

No runout at all would be ideal. Wouldn't perfection be great!

I am not sure what the least acceptable runout should be. I have only recently purchased a gauge and the runout I got on my latest 308 Win loads ran from a low of .002"(4 out of 15) to .007-.008 for the rest. I think that is not good.

I am using Lee dies. I think that a better bullet seating die would go a long way toward correcting my runout problem. If so, what bullet seating die would you recommend ?

I am using Winchester Match Brass.

I bought a Hornady Consintricity tool and labored over checking and fixing run out. And what a lot of guys are saying I found to be true myself. You can over do the run out thing but I still like my runout to be good but it's not the end all. I stumbled on a technique on a utube video where when sizing (and this works with Lee dies as well, they're fine) just turn your brass case about 180° and send it up one more time. I have never found a loaded round not meet my consintricity restrictions on rounds that I double sized like that. Not once.
Now, nobody ever videod the inside of a chamber upon ignition but 50k to 60k psi is some serious instantanious chamber pressure and we all know that case expands and fire forms to the chamber and even hs a touch of bounce back. So it's likely that a large portion of that bullet alignment is done automatically anyway which is why guys like F Class John also claim consintricity isn't that serious of an issue and other processes of our reloading may actually be more important like full length sizing, shoulder bump, neck turning, consistent seating depths & things like that. Just things to consider.

 

[Webster]

I bought a Hornady Consintricity tool and labored over checking and fixing run out. And what a lot of guys are saying I found to be true myself. You can over do the run out thing but I still like my runout to be good but it's not the end all. I stumbled on a technique on a utube video where when sizing (and this works with Lee dies as well, they're fine) just turn your brass case about 180° and send it up one more time. I have never found a loaded round not meet my consintricity restrictions on rounds that I double sized like that. Not once.
Now, nobody ever videod the inside of a chamber upon ignition but 50k to 60k psi is some serious instantanious chamber pressure and we all know that case expands and fire forms to the chamber and even hs a touch of bounce back. So it's likely that a large portion of that bullet alignment is done automatically anyway which is why guys like F Class John also claim consintricity isn't that serious of an issue and other processes of our reloading may actually be more important like full length sizing, shoulder bump, neck turning, consistent seating depths & things like that. Just things to consider.

I always wondered if the case expands and the neck doesn't even touch the bullet as it leaves the neck? When the bullet reaches the rifling you have about 8000 PSI expanding the case.

 

[DShortt]

Dirty shell holder will induce run out, I try and clen groove every loading session.

I wonder how many people don't always use the same shell holder, also.

Details matter.

 

[ELR LVR]

Lots of great advice here,
The only other thing I might add if nobody has mentioned it yet
Excessive neck tension can cause the shoulder to deform/ collapse enough when driving the bullet into the neck to cause one side of the shoulder to deform more than the other
Resulting in excessive runout
For instance, lets say the neck is fighting bullet being seated
Something is going to give and that something is the shoulder could collapse, then bounce back off center,
even if slightly, Maybe the shoulder collapses under pressure but then bounces back, unevenly though.
It would not take much at the shoulder to see a larger difference out at the tip of the bullet being there is a distance ratio.
.001" off at the shoulder could show .010" at the bullet tip.
Check the runout on the neck of your cases BEFORE seating a bullet to be sure you are starting off straight to begin with
if then you seat a bullet and suddenly runout is high,
.that could indicate what I am describing.

 

[JAlfred]

Yea, the gauge comes in handy for setting up new dies but that's about all I ever use mine for anymore.

Or figuring out you have a bent stem on your recapping die.

 

[ISS]

Simple Answer: seat the bullet halfway into the case. Lower the ram, rotate the case 180* and seat.

If your original runout was .001" or less, be happy! If it is more, and my trick does not get you to that .001", get a better set of dies. I am in process on a live varmint rifle to be able to consistently hit Rockchucks at or past 1000 yards. Six inches wide, and twelve to fifteen inches tall. I will likely go with a set of Whidden dies. I have gravitated to them in the last year where 1-1.5 moa accuracy is needed. Depends on results to make the decision.

Good Luck,

ISS

 

[ArtinNC]

All this fancy things to check Bullet Runout is not needed , If you have a bullet seating die made with the same reamer that your gun was chambered with (( Wilson stile )) , You are good to go , and it can't get any better with that set up . End of story . So when you have a new barrel chambered have the gun smith make you a seating die .