Neck expander size

So I’ve been doing some reading and watching some videos and unfortunately the rest of the world does all their testing with copper jacket bullets. So for cast I am wondering if I am using a .310” projectile for my 300AAC should I be using a .310” expander during the sizing process? With a .310” sizer ball the neck should spring back to .308-.309”. My current sizing die has an expander that measures .3067”.

Also currently for my brass I use a 30 Luger expander die to flare the brass and dump the powder. I haven’t seen any accuracy gain or loss from using it but I’m trying to tighten my groups up from the 3” average I’m getting at 100 yards.

Also I did search through the other threads and I couldn’t find any real useful information. I could be searching for the wrong thing I guess because surely somebody has thought about this before me.

Normal practice is for the expander plug to be 0.002" smaller than the bullet.

I use this,stops the case from swagging your new boolit down .Which in turn helps accuracy a BUNCH !!
http://noebulletmolds.com/NV/product...omh3ktkfffist3

I too use the NOE buttons for the LEE die. For my .310 boolits I use the .312X.308 which sizes the whole length of the neck to .308 which gives you your 2 thousands neck tension and just barely turn down to let the next step of .312 to flair the top of the neck to your desired belling. Boolits start straight and seem to be really consistent on tension and runout.

I use and have quite a few of the noe expanders. They work great. I use them the most for lead pistole rounds but that’s what I have been loading lately

I’ll have to look but I think I have a .311 expander I’ll have to try and put up some results and see if I get any accuracy gain.

I use the Noe expander plugs and use either bullet size (counting on spring back) or .001 under. I haven't seen any difference on target, one to the other. Gp