Neck seating lubrication advice

[PeteFox]

Yes
I do turn necks, but I don't use a tight neck chamber, I turn, or skim might be more correct for two reasons.
1. concentricity
2. neck tension
neck thickness is 0.0125". I use a 0.307 bush for sizing and a .2825 expander (this is for 7mm)

I am travelling until September and I am operating from a tablet so I can't really access all my data.

But I can say:
1. a .2825 mandrel produces tighter groups than a .2835 mandrel using the procedure described and
2. a tighter velocity spread, SD of around 6. this is across 20 rounds, not 5.

I don't think my rounds could be moved by hand.

[wsftr]

Thanks.
I ended up with an average chrony SD of 6.8 for the .306 mandrel and 7.2 for the .3075, sample size is over a hundred for each.
I found the average MR is similar between the two however there were days that the .3075 absolutely hammered relative to the .306 mandrel loads.
I still need to pick apart the group size/MR/SD of those groups so there might be something I am missing there, but chrony data hasn't really shown anything up...but I am going to repeat on another barrel as maybe this barrel is the larger noise factor.

[PeteFox]

Yes, and the problem is attributing an improvement or it's opposite to one factor, when it might be something else entirely.
The rabbit hole