Look on gunbroker for a savage in 300 RUM or 375 H&H it will give you the bolt head and length you need. They are discontinued but can be found from time to time for about $500 dollars. I convert them to 458 lotts and one 470 capstick another to 416 Rem mag. I do have a factory one and it slight but the 300 RUM is abbusive even for me in a light rifle. It will hurt to shoot.