I can't seem to find one anywhere I have rcbs FL sizer already.

I've got the RCBS Shiloh Sharps set. What I did to set up the die as a neck sizer is to put one of those spacers that come with a set of RCBS .38/.357 mag dies under the locking ring after I set up the die for full length resizing. If I remember correctly, they are a tenth of an inch spacer and they work great neck sizing the brass and when I want to full length size or convert some .45-70 cases, I can just remove the spacer without having to change any die depth adjustments. I also discovered that because the Hornady .45-70 brass is only 2.0" inches long it makes perfect .40-65 brass without having to trim of anything extra.

Thanks for the tips I'll try that.

I lapped out my fls die so the id of the neck is .409”.  I have quit using it for now and just thumb seat the bullets.  I do use a Lee fcd to remove the slight flare in the mouth. It also keeps the bullet in the case.   

FWIW,
Steve

Thing about neck sizers they reduce a fired case neck enough to hold the bullet firmly. Final size is done by the "M" die expander plug. Ideal is very little expansion while giving minimum flare, just enough to allow the bullet entry. Flare is removed when the bullet is seated. It's a 3 die job.

Whole operation very little brass working and minimum bullet distortion. When my 38/55 CPA was delivered 1996 bought 500 new WW cases Sized 150 to 32/40.  350 cases left as 38/55 have been loaded many times, lost count how many. Single case at least twice a year perhaps more. 30 times per case ? Annealed and trimmed when the brass needs it, you can tell by feel as it's sized. Just reloaded all, count was 330 cases 20 lost, none due case failure .

Boats

If you still need one I can check my old BPCT stash.

Triple E wrote on Jan 16^th, 2026 at 8:17pm: