I noticed a couple of interesting barrels on Gunbroker...

[Otony]

......none of them are my auctions, but a search in the Rifle Barrels section will pop up a .257 Roberts and a 6mm BR, among others.

[NVBighorn]

Are they Savage barrels? I don't see a 257.

[Otony]

All meant for the Savage 10/110, but several makers.

Go to Parts, then subsection, Rifle Barrels. Once there, type Savage into the search engine. Plenty will pop up, not all for 10/110 rifles, but simply sift through the results (one page worth if I recall correctly) and you will find a.257, a 6BR, and even a 6 PPC.