475guy,

Sorry to burst your bubble but you will not get a 500 grain bullet to 2700 fps with a 450 Rigby at anywhere near safe operating pressures.

The 450 Rigby is essentially the same cartridge as a 450 Dakota and is slightly larger than a 460 Weatherby (by about a grain of water). Loaded in the mid 50 ksi range it will provide you a muzzle velocity around 2400 fps with most 500 grain bullets. Loaded to low 60 ksi range the muzzle velocity will be around 2480 fps with most 500 grain bullets. Loaded to 70 ksi you will get a muzzle velocity around 2600 fps with most 500 grain bullets. Loaded till the bolt blows out the rear of the rifle you will get a muzzle velocity, which is probably a bit more than 2600 fps with a 500 grain bullet, but I sure as hell don't want to find out what is it actually is!

The Rigby is factory loaded to around 50 ksi and achieves a muzzle velocity of 2350 fps with a 500gr Woodleigh. I personally see no need to improve on that!

Scott