When measuring loaded ammo runout, where do you measure?

[BurnOut]

At the bullet ogive? I just received the 21st Century runout checking setup, and I'm seeing some pretty horrific stuff... but then I'm also measuring forward of the ogive by probably .150" or so. Either way, I'm seeing a lot of inconsistency that I wouldn't expect to see given my equipment (Forster press and dies, 21st Century mandrel expander) and components (fire-formed Winchester brass and Berger Elite Hunter projectiles).

One round will show a nice, .0025" runout, and the next round, prepped and loaded with the same techniques and hardware, will show .009"... or worse. My money is on operator error, but I'll be damned if I can figure out where/how...

 

[Supersubes]

Everywhere. Body in several places, neck, and bullet. Start with a few fired and deprimed cases, preferably ones that aren’t dinged up. Should be very straight. Now take them through your current reloading process measuring after each step. Could be just one process, or the combination of several.

 

[L.R.Novice]

I use to measure every case on the neck just reward enough of the mouth to prevent inconsistencies after sizing. I also measured every bullet just reward of the tip after seating.

As an aside, one day I shot groups with various amounts of runout and didn’t find any correlation between group size and measured runout. I now only measure a couple to verify nothing is screwy in my setup.

 

[ZiaHunter]

+1 on what Supersubes recommends. Check runout each stage of the reloading process to determine where it is occurring. Once you diagnose it you can work on correcting it. Drawing the expander plug through the neck during sizing is one of the main causes of runout. Regardless of how you expanding the neck, make sure the inside of the neck is properly lubricated. Probably not a die alignment issue since you are using a Coax. I measure at the ogive.

 

[TripleBull]

I used to measure in 5 spots: 3 on the case and two on the bullet. Now I'm down to measuring the case ~2mm from the mouth and the bullet ~3mm from the meplat. I'm seeing more correlation with performance from those measurements than the ones I dropped.

 

[BurnOut]

Everywhere. Body in several places, neck, and bullet. Start with a few fired and deprimed cases, preferably ones that aren’t dinged up. Should be very straight. Now take them through your current reloading process measuring after each step. Could be just one process, or the combination of several.

Yeah, that's what I'm going to have to do. At this point, I don't have any fired cases that I haven't resized, etc..., so I'll have to run through this batch of ammo, then get after it. I appreciate the feedback.

 

[padom]

Ok, so there is "runout" and "total indicated runout"... Which number are you providing? If your seeing .009" total indicated runout than your actual runout is .0045" (One half your TIR). A lot of people get this messed up. You have to cut your TIR number in half to get your actual runout number.... Now, with that said, TIR is still a good measurement of round to round concentricity... But, your Forster setup isnt putting out .009" runout either. Its putting out a max of .0045" and something in your process is causing this. Anything under .005" runout is actual just fine. Sure, we all want the .001 runout number but anything under .005" is good to go.

I use your EXACT setup. Forster Co-Ax, Forster FL sizing die honed to size neck .004" under final sized neck diameter with expander removed. I set final neck tension with a 21st Century TiN turning mandrel for a final neck diameter of .002" neck tension. My runout is consistently in the 0.0005"-0.0015" TIR range meaning my actual runout is half those numbers. I also anneal every 3rd firing on Lapua brass.


So, a few questions...

1) Is the allen die float set screw on your Co-Ax setup properly. You should be able to slide your die in and it should wobble so its "Floating" That set screw should NOT be tight
2) Are you annealing? If so, how often?
3) How many firings on that brass?
4) Have sized a case with your Forster FL sizing die then measured the runout on the neck? Take the average of 5 cases.. What is your actual runout? (Half your TIR)
5) Have you then run that case through your 21st Century Mandrel and measured runout? Whats your actual runout?
6) Then seat your bullet and measure runout right at the ogive of the bullet where it contacts the lands. Whats your actual runout there?


I am pretty positive you will find your cause following the above steps but honestly your setup is producing pretty straight ammo already. If you told me your actual runout was .009" and not your TIR than I would be concerned. I suspect your giving us your TIR.....

 

[padom]

Yeah, that's what I'm going to have to do. At this point, I don't have any fired cases that I haven't resized, etc..., so I'll have to run through this batch of ammo, then get after it. I appreciate the feedback.

What caliber are we talking here? What rifle? 308? 6.5cm? Semi or Bolt gun?

Measure 5 of those cases you have sized already and post the 5 numbers you get. Your actual runout will be half of what you see on the gauge. That will at least tell us what your getting before seating bullets.... And those Winchester cases arent going to be as consistent as say Lapua so I would also measure runout of those sized cases on the inside of the neck about half way in. Post those 5 numbers as well...

 

[BurnOut]

Ok, so there is "runout" and "total indicated runout"... Which number are you providing? If your seeing .009" total indicated runout than your actual runout is .0045" (One half your TIR). A lot of people get this messed up. You have to cut your TIR number in half to get your actual runout number.... Now, with that said, TIR is still a good measurement of round to round concentricity... But, your Forster setup isnt putting out .009" runout either. Its putting out a max of .0045" and something in your process is causing this. Anything under .005" runout is actual just fine. Sure, we all want the .001 runout number but anything under .005" is good to go.

I use your EXACT setup. Forster Co-Ax, Forster FL sizing die honed to size neck .004" under final sized neck diameter with expander removed. I set final neck tension with a 21st Century TiN turning mandrel for a final neck diameter of .002" neck tension. My runout is consistently in the 0.0005"-0.0015" TIR range meaning my actual runout is half those numbers. I also anneal every 3rd firing on Lapua brass.


So, a few questions...

1) Is the allen die float set screw on your Co-Ax setup properly. You should be able to slide your die in and it should wobble so its "Floating" That set screw should NOT be tight
2) Are you annealing? If so, how often?
3) How many firings on that brass?
4) Have sized a case with your Forster FL sizing die then measured the runout on the neck? Take the average of 5 cases.. What is your actual runout? (Half your TIR)
5) Have you then run that case through your 21st Century Mandrel and measured runout? Whats your actual runout?
6) Then seat your bullet and measure runout right at the ogive of the bullet where it contacts the lands. Whats your actual runout there?


I am pretty positive you will find your issue following the above steps.

Good point, re: runout vs. TIR... the numbers I posted are TIR... so halve the values I posted for the TIR. In any event, in response to your questions:

1) I'm pretty sure that this is adjusted properly... I haven't touched it from the factory setting. I'll check it when I get home tonight, though.
2) Not yet.
3) One firing; it was purchased as virgin, had the neck expanded with the 21st Century mandrel, and loaded. For the reload, I bumped the shoulder back 1.5-2 thou.
4) I'll have to wait on this one... every case I have has been run through the Forster FL resizing die AND the 21st Century mandrel
5) This I can do; I have about 30 cases that have been FL resized and run through the mandrel expander.
6) I can check this as well... I should be able to blacken a projectile with a Sharpie, then mark the ogive by running it into the Hornady bullet comparator. It won't give me the exact ogive, but it should be pretty close.

Now that I am thinking about it more, I think that I may have found a possible source of my issues... the ammo in question is 338 Win Mag, obviously a long case. Until yesterday's mail delivery, I only had the standard expander die body from 21st Century... which wouldn't allow for a full stroke of the press handle before the case would bottom out in the die. Consequently, pretty much every case I ran through that die bottomed out... I didn't think that I bottomed them out hard enough to deform the cases, but it's certainly possible that I am wrong. In any event, I now have the extra-long expander die body, so if that's the source of the problem, it has been eliminated.

One other thing worth noting... as part of my case prep, I also trimmed the cases to length using the Sinclair/LE Wilson micrometer trimmer, and the cases wouldn't snug up in the case holder... they'd slide in all the way to the belt. There didn't seem to be much play at the case mouth... it's almost like they were juuuuust about to snug up on the taper when the belt would hit the case holder. The cases would spin within the case holder when getting trimmed unless I held the base of them to prevent it. I did my trimming after FL resizing, so I have to wonder if my die isn't squeezing the cases down too far. Not that I think that this explains the TIR numbers that I'm seeing, but it's just something else odd that I noticed.

I appreciate the input and will post up once I get a chance to check the die set screw and resized/expanded case concentricity.

 

[padom]

One other thing worth noting... as part of my case prep, I also trimmed the cases to length using the Sinclair/LE Wilson micrometer trimmer, and the cases wouldn't snug up in the case holder... they'd slide in all the way to the belt. There didn't seem to be much play at the case mouth... it's almost like they were juuuuust about to snug up on the taper when the belt would hit the case holder. .

Are you just sliding the cases in? Or are you putting them in the case holder and tapping them on a firm surface like in the Wilson instructions? They still dont snug up when doing that? If thats the case I would contact them about it. A spinning case cant be giving you consistent trim lengths from case to case.. Your using this LE Wilson case holder for your brass/trimmer right

• L.E. Wilson #: NCH-264WN

 

[BurnOut]

Are you just sliding the cases in? Or are you putting them in the case holder and tapping them on a firm surface like in the Wilson instructions? They still dont snug up when doing that? If thats the case I would contact them about it. A spinning case cant be giving you consistent trim lengths from case to case.. Your using this LE Wilson case holder for your brass/trimmer right

• L.E. Wilson #: NCH-264WN

I'm tapping them in on my reloading bench, but they'll only go so far due to the belt contacting the case holder. The same case holder works great for my 300 Win Mag cases, so I'm wondering if it's something to do with the FL sizing die... as for the part number of the case holder, I'll double check it when I get home, but I'm pretty sure that's it.

 

[Deleted member 10043]

<.005 TIR mark bullet so the load into the chamber is in the same spot. Subsequently, they will exit the barrel in the same manner. Tighter groups.

 

[cmrizzo]

I'm tapping them in on my reloading bench, but they'll only go so far due to the belt contacting the case holder. The same case holder works great for my 300 Win Mag cases, so I'm wondering if it's something to do with the FL sizing die... as for the part number of the case holder, I'll double check it when I get home, but I'm pretty sure that's it.

Are you by chance using the "Standard" case holder for fired cases vs the "New" case holder? That will make them just loose after sizing....

 

[jonesturf]

+1 on what Supersubes recommends. Check runout each stage of the reloading process to determine where it is occurring. Once you diagnose it you can work on correcting it. Drawing the expander plug through the neck during sizing is one of the main causes of runout. Regardless of how you expanding the neck, make sure the inside of the neck is properly lubricated. Probably not a die alignment issue since you are using a Coax. I measure at the ogive.

I don't necessarily agree that using an expander plug is going to cause runout. In some instances, sure, but no in mine. I do things a little differently. I don't neck turn so for me the expander plug is the last thing that touches the inside of the neck of the case. I use Whidden dies and they seem to work well for this as the expander assembly floats.

To me the inside of the neck is the most important indicator prior to seating. I measure this using a test indicator setup inside the neck rather than outside. I guess if I was turning necks the outside would be fine. On factory Hornady Creedmoor brass and using my method I rarely see more than 0.0015 TIR and thats good enough for me. That's on the inside of the neck before sizing. Seating bullets then usually ends up just like the neck and doesn't show any more runout.

It took me a while to get to this point. I ground the expander button down to exactly where I want my neck tension and still use bushings but since I'm not neck turning the expander ball is super important to me. Different strokes for different folks I guess. Not saying neck turning is bad. I would do it if I had time but I'd rather be shooting.

 

[BurnOut]

Are you by chance using the "Standard" case holder for fired cases vs the "New" case holder? That will make them just loose after sizing....

I don't think so, but I'll double check. The thing that's really puzzling for me on this particular issue is that the same case holder does great when holding (fired and resized) 300 WM cases... it's just the 338 WM cases that seem to exhibit this behavior.

One other thing worth noting on this issue, I believe that I have inconsistent neck thickness on these cases. While recognizing that it's not really the right tool for the job, I used my digital vernier caliper to check case thickness at the neck, and found it to vary by up to .003" around the case mouth. This measurement might change some if I use the proper tool (a tube mic), but I can't help but wonder if that's part of what's going on. I have the ability to turn the necks, but was hoping to be able to avoid doing so.

I have so far checked fired/de-primed/tumbled cases for runout, and things at this point seem to be okay... I just need to get off my ass and continue to push them through the rest of the case prep process as far as resizing/bumping the shoulder, expanding the case mouth, etc...

 

[cmrizzo]

I don't think so, but I'll double check. The thing that's really puzzling for me on this particular issue is that the same case holder does great when holding (fired and resized) 300 WM cases... it's just the 338 WM cases that seem to exhibit this behavior.

One other thing worth noting on this issue, I believe that I have inconsistent neck thickness on these cases. While recognizing that it's not really the right tool for the job, I used my digital vernier caliper to check case thickness at the neck, and found it to vary by up to .003" around the case mouth. This measurement might change some if I use the proper tool (a tube mic), but I can't help but wonder if that's part of what's going on. I have the ability to turn the necks, but was hoping to be able to avoid doing so.

I have so far checked fired/de-primed/tumbled cases for runout, and things at this point seem to be okay... I just need to get off my ass and continue to push them through the rest of the case prep process as far as resizing/bumping the shoulder, expanding the case mouth, etc...

You will definitely get more accurate readings using the proper measuring tools. As far as neck turning, if you have the ability then I say at least uniform them. The case holders do make a difference and for future purchases, I'd always get the "new" case holder as I've been able to use them on both FL sized and neck sized cases.