Data Needed - 257wby with 117gr Gameking

[Mad_Mikee]

Anyone loading their 257wby with the 117gr Sierra Gamekings?

I dont have a reloading manual with anything like this in it.

I'll be using 7mm Rem Mag brass necked down so i'll want to keep my loads 1-2 grains under max.

Any sort of starting point with powder, charge, etc would be appreciated.

 

[sbtennex]

Didn't know this would work. Go to a Hodgdon or similar site. Think I'd use use a start .257 load of anything to fireform - all those weird radii on the Roy. Hard to measure for a headspace reference point. Only thing different that I know of between the two is the rim is a hair narrower on the Roy (diameter, not thickness which I don't know), about 1 thou. Me? I'd use .257 Roy brass -removes any doubt. Hope you have a detailed case size spec diagram for both. Good luck!