Forming 300-338 Norma Improved from 423 Dakota

[scottwwv]

I purchased box 423 Dakota in hopes of forming them into 300-338 Norma Improved cases with a 35degree shoulder. I purchased dies from Whidden. One of each .430, .400, and .370 neck form die as well as a custom full length bushing sizer. I lube then size to .430 then lube again size to .400. I am unable to size to .370 without the neck shoulder junction folding in upon itself. Do you have any recommendation on how you would size down.
Are you neck turning at on stage or annealing at this a certain size or should I get say a .385 die and add to the mix? What are your thoughts and steps?
I know some members here have been through this. I am just trying to get ahead of the learning curve without wasting alot of cases.
Thanks

 

[tim_w]

Mudrunner or was it Swamplord and IdahoCTD are the guys to ask on that they both have made wildcatts off those cases. I just picked up some 423 from the latter a week ago for a 338 Norma Impr I have planned. For the cost it was better than sizing down and blowing out 338 LM cases.

 

[scottwwv]

I am having trouble getting the neck smaller than .400 leaving the inside diameter .370. I hope you can find a good way to go smaller than that without the neck smashing inside the case.

Mudrunner and IdahoCTD are the guys to ask on that they both have made wildcatts off those cases. I just picked up some 423 from the latter a week ago for a 338 Norma Impr I have planned. For the cost it was better than sizing down and blowing out 338 LM cases.

 

[tim_w]

are you getting a doughnut inside at the base of the neck?