Going back to the OP question and skipping all the weirdness in the middle of the thread - I had high hopes for the 350 Legend but was pretty disappointed in the execution; a lot of the details changed it from something with a lot of potential to something proprietary and limited.
I have a better alternative though (and did this long before the 350 L came out) - a wildcat I call the 358 Herrett AR. There are other versions of this floating around too - it's essentially a 6.8 SPC case blown out and necked up using shortened 357 Herrett dies. I chose the .358" rifle bore for versatility and the 1:14 twist rate, but some other variations use a .357" tube and 1:20 twist.
The long and short of it is this round will exactly duplicate 20" 35 Remington ballistics, but from a 16" AR15. Primarily that means 200gr @ 2150 fps, although it'll handle heavier or lighter bullets easily. I've made a couple of 10.5" versions that work well too. It also does double duty with heavy (250-300gr) cast subsonics too, somewhat like the dual purpose 300 Blk.
If a guy is interested in wildcatting, this one is easy to make with a 357 Herrett reamer, and makes a lot lighter package than a 358 Win AR10. I'm not in business making these and am not looking for any more work, but am happy to share info if someone's looking to try this.
200gr Hornady SP and 255gr cast hollow point (subsonic) shown, with 300 Blk on the left for comparison:
A big hollow point changes the world of subsonic terminal performance:
Feed ramp mods for large flat nose bullet profiles. Not necessary for pointed bullets.