Yes there is a new big bore cartridge in the works not for elephant but should be popular .
It's the 400 legend based on straight 6.8 spc round .It should have more knockdown Than a 350 legend .I want it in a ruger mini 14 .It should be a fun shooter in what ever it comes in

Interesting. SAAMI specs are showing pistol bullets (.400) at over 2200fps?? That's going to need to be a pretty stout pistol bullet to hold up, I'd think?

Currently guys with similar .400" wildcats like the 40GPC, 400AR are using 180 + 200gr XTP's, 200gr SST (as well as TC's version with the yellow tip, Barnes 195 MZ, or the Knight 175gr version. You can also have Fury, Makers, Vollmer or other custom bullet manufacturers make bullets for your gun. So there are options.

I have a similar concept 40x1.8 based off of 30-06 brass that's a little faster. 200gr xtp out of a 16" barrel 2600+fps, 22" barrel 2750+fps. 200gr SST chrony average 2761 fps for the 22" barrel. I hunt with the barnes 195 though in an ar15. Long for weight copper 195 maxes out about 2450 fps out of a 16" because it takes up more case capacity due to COL restrictions in ar15 mag. My hunting load is a 195 barnes right at 2400fps and zips right through deer doing decent damage. I've been reluctant to chamber it in a 308AR so far since with the 800series bolts it works in ar15s.

I bet they will have all new bullets for it .It will be an awesome round in the ar15 .I want one on a mini14 ruger .I hope it makes it big time a big bore with out big recoil is alot of fun .