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.