The reason Federal makes #7 TSS is because 9 isn't legal in some states nor is the .410. TSS is such a bust that Stevens has designed a .410 around TSS #9.
https://www.savagearms.com/firearms/shotgun/stevens-series/301-turkey

Now the company named after the greatest inventor of modern firearms has a line of TSS shot for turkeys:
https://www.mackspw.com/Browning-12-Ga-TSS-3-1-3-4-oz
When someone says that everyone who uses TSS has a dense head and that same person rants against its use one has to wonder who has the dense head. Stevens, Federal, Browning et al.?? Nah...
BTW, Federal has used Tungsten #7 15 g/cc for close to 15 years in the Heavyweight series, but only last year introduced the TSS load which is tungsten shot with a specific gravity of 18 g/cc. Gil