So I just read
This Post and thought it was very the interesting. There is/or at least was a savage bolt gun in 5.7x28mm as well the Thompson Center offering in addition to the more well know FNH offerings and the AR-5.7 uppers.
I don't really see a 5.7x28mm firearm in my collection, but i must say it is beautiful niche filler
Savage Bolt Gun