BuffloBob,
While I've never used a Redding press, I do know that the larger the caliber you swage, the more stronger your press need be. I believe the presses made by the Corbin brothers are at a minimum twice as strong as any reloading press. That is for a good reason. Even with pure lead those .400+ calibers require lots of force.
For the calibers you mentioned, you will need to have your dies made to order. Other than .224, .308, .357, and .429 caliber, others are hard to find "off the shelf", especially with the nose forms you prefer. While it is true, you can get 'reloading press configured' dies from some die makers, why pay about the same for them as you would for Walnut Hill dies, with the base and point forms you want? About "some" tin in your core mix: You are flirting with broken dies putting anything other than lead in your core material. True, it depends upon the caliber you are swaggiing, and the type of die used, but you run the same sort of risk a reloader does keeping his powder in an unmarked can... As the months go by, and you acquire different dies, you forget about the tin percentage is. While it worked great in your .257 bullets using Walnut Hill dies, it breaks your $200 die for your .44 Magnum. If you want to get into bullet swagging, I recommend you get your Walnut Hill press now. Even if you deside swagging isn't for you, you can sell your outfit for very close to what you pay for it. When you make your order for the dies, ask Mr Corbin what percentage of tin/antimony is allowable, and them make very sure it's well marked and doesn't get confused with your other supplies. In that regard I strongly recommend you keep a log book concerning your swagging efforts/decisions. You'll find it will save you a lot of time.
