I posted on the other questions as well, and want to express, that the newer gun, especially the big 10 bore actions are pretty much way beyond what the early 1900s action were in a metalurgical
sence. The difference that I have seen is with repsct to fit and finish. i recently fired a converted 12 gauge in 450#2 with a very stout load, and it performs very well indeed, and was shot a great deal befor giving it to its customer.So, In my very humble opinion, a good conditioned well made 10 bore is more than enough for the big .600 provided it is loaded up short of the full whoop. It may even been ok for that, but we no longer have mastodons down where I live, but do have some of there bones.....
Cheers guys Have fun, shoot what you can afford....safetly