Last time I asked a question like this on the site, I ended up with a .20 vartarg project.

Tell me about the .300 whisper. Really like the .221fb case and low charge, LOW recoil required (due to injury), bullets from 125gr to 210gr. Looks to be accurate up to 300yds. Is it quiet? 1,125 ft/s is sub-sonic, however, there are loads for it that are faster. Why is this discussed as an attribute of the caliber?

My .243 is too much recoil. Maybe should stay with a .223 with heavy bullets instead, but a small charge .30 caliber is interesting!

Assume the .300 whisper is as long as the .223 oal due to bullet, so will the cartridge feed in the stock Savage mag?