shove a 30 deg shoulder back to 20?

[constructor]

How hard is it to change the angle on the shoulder?
I am thinking about necking down some available brass and changing the angle so it will feed in a gas gun.

 

[constructor]

In this case I want to leave the base of the neck in the same location and push the body/shoulder intersection back.
I know it can be done in several steps because I've shortened and necked the 500 Jeffery down to 338.
This time it's .284 down to .264 and changing the shoulder from 30 to 20. Has anyone done this and can it be done in 1 or 2 steps? Should I have a die cut with a 10 degree angle first and then go to the size die with a 20? This would probably be safe and dies are only about $80 piece. It just takes 3 months!
Maybe I can find available dies and mill them to a shorter length.

 

[robbor]

Im sure it can done, only problems I have heard of is forming forming steep shoulders of more than about 35degrees with a die alone.

 

[2644ever]

I assume you already got the reamer ready for your project, you could already make a forming die with it, using blank dies. And if your project doesn't involve anything more complicated than necking down and changing the shoulder angle on a .284, try running a .284 Win case in a 6.5 Rem Mag die, lathe shortened to eliminate the belt recess and it should drive you quite close to your aim.,hint: I've tried it already!)