I use whidden full length size dies and the Forster ultra micrometer seater die. Love both. I used to use only Redding competition seat dies but the last two I bought were stinkers.
Dasher reamers are all over the place in the base dimension or .200 line diameter. Suggest a Harrels FL bushing sizer. Harrels offers Dasher dies with different base dimensions. There's a chance a Redding or brand X die will not size the base properly. If you can get the .200 line dimension of the reamer used, post it here.