I use an old RCBS JR press I got right out of high school, 39 years ago. It works just fine. The Rigby is an easy one to reload.

For one thing, with that tremendous powder charge a minor variation in the powder drop doesn't have much effect on accuracy or pressure. I use a powder measure when loading the Rigby, while I dip and weigh for the smaller, hotter calibers. When I had a 416 Remington I always weighed every charge. It seemed to be a highly sensitive round to any minor variations in components, while my two Rigbys have not been.

Any good modern press will get you going, but I wish the JR press had a longer stroke when it comes to seating bullets.