Here are a couple of ideas for a .500 on the cheap.

I know you want a bolt gun, but a Ruger #1 can be made into a .505, or other .50 for a song, compared to a custom bolt gun.

Now that the rimmed 50s are cheaper to load, i.e., Lyman dies and Starline brass, a very capable .50 could be assembled for under $1500 on a Siamese 98 action or a Ruger #1. A 50-90 with smokeless loads in a 98 or Ruger #1 will provide a lot of push on both ends!

Otto

P.S. to Curl: What is the lovely underlever pictured in your posts? I have an "Adams" 450 BPE that is very similar, but without the carved fences.