I've been running a few full length 38-55 cases through my 8.15x46r dies to create 8.15x52r cases..   I am getting a little bit of dimpling on the shoulder and the transition from the body to the shoulder.    I know its not terrible uncommon; I've had it happen on occasion in the past when forming commercial and mil. 308 brasss down to the 6.5 redding/.260 Rem though jot as frequently as I am having now.  Past experience is that in most cases fire forming blows them right back out.   it seems more frequent and severe with about 40 Dominion CIL cases---one of which developed a small split coming out of the die.

I have a couple questions:

What causes it to happen ?    I'm using the "imperial sizing wax" what ever it is made out of.  I don't know if more or less would make a difference.

Does brass "harden" simply with age?  The CIL is very clean once-fired in original boxes. It came form an estate sale and I suspect it had been setting on a shelf for quite a few years. I'm wondering if annealing might help?

Yes it is a result of to much lube.
When you size excess lube has nowhere to go so it puddles together and make the dimples.
Try lubing the top ½" of the case only.
It will spread downwards as you size the case.
Sizing in 3-4 series of ½" strokes is also a good idea to avoid lube dimples.

When I use Imperial just put a bit on my fingers every 4 or 5 cases. Handling the case alone wipes it on the base and neck. It takes very little to lube.

Boats

Lube with paraffin.  That avoids wrinkles from lube entirely.

dave

Being from Canada Ive had lots of experience with the Dominion Brass, and mostly bad. I suspect that the main issue is its too hard. Lots of it in factory loadings from 1950's  to 1970's are split at the neck in the new box. So annealing is certainly a must , but it may be beyond fixing ? I would try to obtain some other brass. But for some reason some of their thinner brass cases such as 38-40, 44-40 and 32-20, may be OK