257roberts from 30-06 blanks

to explain what ive done
first i cleaned the brass
2nd trim the brass to 257rbts length in a forster original powered with a drill
3rd slowly incriment form with 7/8" machine bushings (6bushings)
4th deprime and expand mouths to 257
5th turn necks to .0105" thick walls

here is where my problems start
all my lengths by saami specs and real 257rbts cases fired from said 257rbts rifle seem to jive. BUT dummies made from formed brass will not let the bolt into full battery. bolt handle reaches its notch in reciever but wont turn into battery.
what can i try to fix this problem?

You need to size the cases a little more.
It is harder to push the shoulders back the last few thousandths with .30-06 brass. If you are using a C press you will have a worse problem.
A .257 trim die works well but you can do it with a FL die.

Just set your FL die to touch the shell holder.
Size a case. Retract the ram about 1/2" and spin the case and size again. Repeat for 3rd sizing. Check fo fit in your rifle.

As EDG says it's probably just sizing the shoulder.

Second idea is it could also be a tapered neck that is thicker at the base than the mouth. That could be either a neck turning issue or just a sizing issue.

I guess there's a chance the OAL is wrong and the neck is interfering with the chamber step, but you seem to have that covered. Still, compare to the old genuine cases.

Sometimes Full Length dies aren't tight enough, even if they stay in contact with the shell holder during sizing. In that case, get a Redding FL die, or a Small Base die, or file some off the bottom of your die, or off the top of your shellholder (the cheapest option). Then mark that SH carefully so you don't use it for anything else.

thanks guys i like the shellholder idea a lot. necks are forster turned to 0.0105" from mouth to shoulder

The base of the 06 blanks might also be too large for your 257's chamber. You my need a body die also.