Texas10 wrote on Aug 13^th, 2015 at 10:34pm:

I grabbed 3 of the Winchester brass. The necks measured .340 at the mouth, .423 to .424 at the shoulder, and .455 about .200 above the rim. And yes, that grams reference was a typo. Should be grains.  ::)

My measurements are as follows:

Fired Brass
Neck dia.    .340"
Length at Shoulder using .375" collet    1.784"
Shoulder dia.   .422"
Gasring dia.    .456"

Sized brass using my Hornady sizing die modified to take an Redding Neck Bushing (.333")
Neck dia.  .333"
Length at Shoulder using .375" collet    1.780" (could set it tighter if needed)
Shoulder dia.   .419"
Gasring dia.    .453"

Bottom line:  your measurements are spot on.  If you want a sizing die modified as mine, let me know.
keith.herrington@aol.com