In the Micro Actions like a Vixen or Howa, you won’t have enough tennon and receiver thickness for full pressure WSSM. We’ve already looked at that.
Hoop strength isn’t there. I would also wonder about lug strength. Those micro actions are meant for .222, 6mm PPC, Grendel, stuff like that.
They’re just not built for fatter, higher-pressure cartridges. Howa was able to do it in .450 Bushmaster because the SAAMI MAP is 38,500psi, nowhere near 65,000psi of the WSSM.
A good buddy of mine really likes wild-catting the WSSMs, mainly to 7mm. He used a R700 size short action with custom feed lips and magazine work. Spits out 180-195gr with extremely tight ES and SD, yielding sub-MOA groups at ~1 mile even on 20” gong. First time he grouped it at 1710yds, he put 7x 195gr EOLs into 14 1/8” CTC, 5.0fps SD.
My favorite of the factory WSSMs is the .257 cal of course. Smokes the others easily. Load it with the new VLD class of 131-135gr .257” bullets and you’ve got something. It also has a 30˚ shoulder, not a 28˚ like the .243 WSSM. I always wondered how it would do with a 40˚ shoulder and some other bores like 6.5mm and .277”. We already know what it does with 7mm.