request: advice for best concentricity

[bow shot]

Understood. With the Lee collet dies, I wonder sometimes if the collet that pushes the brass against the mandrel causes a compromise condition, ie, where neither the collet nor the mandrel give, and therefore both the ID and the OD end up off a bit. Whatever the case, it looks like I'll need to get a neck trimmer sooner or later.

[bow shot]

'Purchased some Nosler brass yesterday. I'm reading very consistent neck wall thickness: 48/50 cases vary under 0.0015" in thickness (per individual case) and only 2 varied more than that. There was a very tiny thin spot on those two, and the total variation on each of those cases was 0.002"

Case length was also very consistent, 45/50 cases were 1.8355 - 1.8365". Two were 1.8345", and 3 were 1.8375"

I used a good Mitutoyo anvil mic for the readings.

I was also watching Odd Couple DVDs as I took readings, and not running a spreadsheet, so this data should not be submitted to the National Academy of Sciences. Their standards for data collection and observations thereon are much lower.

[bow shot]

...and for what its worth, the variance seems to be local to the outside of the neck.

I gather that because I found that if I measure the neck wall thickness variation on a case, and then measure the TIR on that same case, the measurements are extremely close.

So if I have a case that has 0.001" neck wall thickness variation, that same case will have 0.001" TIR. Maybe 0.0015"

My logic could be off though, I'm open to that.

I forgot what numbers I got with the Hornady brass...maybe Its here in this thread...

I've very curious what I get for bullet TIR when I seat with the Forster. Time is not on my side, lately...

[bow shot]

..that I did indeed measure up some of the Hornady brass. There was more variation in the (individual) neck wall thickness of the small sample of the Hornady than there was in the 50 pcs sample of the Nosler, by about .001". As I recall that (hornady) was a kind of quick check...

[bow shot]

This is just a FWIW...

36 pieces of Hornady 3x fired brass; neck wall thickness measurements (rounded to 0.0005"):

12 pcs: 0.0115" - 0.0125" (0.001" variation)
16 pcs: 0.0110" - 0.0125" (0.0015" variation)
8 pcs: 0.0100" - 0.0130" (0.002" variation)

The last operations before measurement were collet neck sizing, faint VLD chamfer, and faint outside deburr. I don't think I actually removed any metal in these processes). Brass was not tumbled. I did scrub clean the ID of the necks of the worst cases, and re-measured, there was no change.

If I get industrious, I'll get the TIR of the empty brass and then the bullet after going through the Forster seater. Perhaps do the same for the nosler

[Rick in Oregon]

bow shot: If you really want to control this TIR thing, do yourself a favor and get a Holland (or Sinclair) VLD chamfering tool. I use the Holland unit, I think it's 8 degrees, carbide multi-flute cutter with a nice robust handle.

Once chamfered, I always inspect every case neck under 10X magnification (machinists loupe) for any defects. You'd be amazed at the crap quality of chamfer the mass marketed tools give a case neck with their 45 degree chamfer. They leave micro burrs that affect bullet seating more than you'd ever imagine that can easily move a bullet off center axis.

Since I started using the VLD chamfering tool, I notice all my bullets in all caliber cases seat much easier (Redding Comp Seaters), my TIR is much less and more consistent, and the paper targets reflect just a bit more accuracy by way of more evenly round, dinky groups. This is one of those not so often thought of tools that can and does really make a difference.

[bow shot]

You know, I may just do that. I'm currently using a $10.00 Lyman. 'And now that I think of it, I've got a loupe sitting in my drawer!!. And I can see how a tiny burr on one end of the bullet (from the brass case) can cause a lot of tilt.

As I scour the forums, I see that I should have first devoted attention to some more influential variables... I'll attempt some bedding work over the next few weeks. A skilled riflesmith has offered to inspect and improve my crown too.

But, being the type that I am I'll be pursuing runout negation as I go..

[bow shot]

another FWIW...

50 pieces of new unfired Nosler brass; neck wall thickness measurements (rounded to 0.0005"):

46 pcs: 0 - 0.001" neck wall thickness variation (per invididual case)
4 pcs: 0.001 - 0.0015" variation

Brass TIR readings:
16 pcs: 0 - 0.001" variation
20 pcs: 0.001" - 0.0015" variation
14 pcs: 0.0015" - 0.002" variation

I'm thinking the measurements for TIR will incline to match the neck wall thickness variation after firing and neck sizing...

Again, if I get industrious, I'll get the TIR of the bullets after going through the Forster seater. Perhaps do the same for the Hornady.

[bow shot]

Rounding #s for the Nolser brass was usually UP. I had no neck wall thickness variation over 0.0015", and barely hit .002" on the TIR. The highest TIR readings were a couple cases that looked like they took a little "peen" at the mouth from banging around in shipment.

[Rick in Oregon]

The TIR measurements of new, unfired or unsized brass is about meaningless there, bud. With all the rough handling it receives on the way to our loading benches, it only makes sense to take TIR readings after firing to check the chamber runout, if any, and after sizing to check your dies and loading procedures.

When sizing, either neck or F/L, leave the decapping stem loose in the die so it will self-center upon exit from the case, which will also help aid concentricity if you're using the expander ball in your dies.

[bow shot]

right... some of them did look a little travel worn.. But I was pretty impressed still, versus some of my other stuff that's been fired a few times.

Rick, I PM'd ya. I'll be loading my son's AR for him... you're an AR shooter, right?

[bow shot]

..that the weather man wil lbe right for a change. Temps in the low 40's predicted for my area! We usually get one minor thaw in January so here's to hope!

Gonna have to get those Noslers loaded up.

Pow pow pow!!!!

[bow shot]

No traction on this over the week end. Rats. It was beautiful here in central NY, but I wasn't able to do much other than esat primers. Used a lee hand tool for this. Very nice; fast and "tangible" compared to my old method, which was using the RCBS JR press.

Spent the time reading Lone Survivor by Marcus Luttrell, the story of the lost heros of SEAL Team 10.

[bow shot]

It seems Rick is right. After seating bullets in the new Nosler brass with the Forster die, the TIR just short of the olgive was all over the map, ranging 0.001" to 0.006". I'm thinking the new brass TIR and neck wall variation is at its worst stage of influence (on bullet TIR) at this step. 'Kind of wish I had neck sized this bunch before I moved on to seating, or went 50/50: half the group seated w/o sizing and half the group neck sized before seating. Oh well, its data for the books at this point I guess. Man, I hope things come out different after firing and going into the first re-load. It may take quite a few days before I can shoot again...

I'm using the Forster correctly; per instructions, which are plain and simple.

[bow shot]

..and has been loaded again. I took some measurements of the TIR of the unfired brass, the necked brass and TIR of the seated bullets. Nothing great to tell, the TIR of the bullets still ranged from about 0.001" all the way up to 0.006". I'll try to post the measurements soon. I forgot to measure neck wall thickness. Rats, rats rats. I'm hurrying and that causes me to miss stuff like that.

It may be that the runout has actually IMPROVED, but seems worse because the 40gr pill is quite a bit longer than the 32 grain. It also may be that firing has "adjusted" neck wall thickness (for the worse) and now is the more appropriate time to trim. I'm speculating here...

Interesting to note: the length of the brass actually shrunk for 1.8360" +/- 0.0005" brand new, to 1.8330 +/- 0.001". Anyone else ever witness such a thing?