That's a good point. Also to allow some younger shooters a try at using a full size center fire rifle w/o being knocked around.

The indoor range I belong to here doesn't allow any centerfire rifles at all sadly, not even in a pistol caliber. Rules are rules, I guess.

Sounds like a nice collection of adaptors. If you have more time and patience than I ever did when I had mine, no doubt you can find the right combination for decent accuracy. They were popular with big game hunters at one time for use in gathering small game for camp meat.