Switch barrel idea.
 

Kinda silly, but why not have a 300whisper/blackout and 338whisper#2 switchbarrel? You could do a 223 barrel or what not also and all use the same bolt. Just a idea and I think it would be ideal for somone with just a 9mm can as it would work with both whisper calibers if used with subsonic only.

FYI 338 whisper#2 is the 338 whisper based on the 221/223 case not the 7mm br :)

I have a Savage single shot 300W now and I fight the urge to have a 338 straight, 338 thumper, 20 Practical, 7mmTCU, etc. barrels for it......:uzi2:
That gun could spend so much of my money so fast. Especially if I had the barrels turned with shoulders so gauges wouldn't be necessary.

There's another Thumper/straight case waiting to be utilized along the lines if .375 X 39, now if you could rebate the rim to .378........

It is far too easy to do. You are just a barrel wrench and vise away. Then you can treat your action as a platform and set up the barrel you want/need as you go - takes about 5 minutes.