Nothing wrong with an 18" barrel, just a bit heavier.

That 16" 6.8 rifle I had or either the 16" 7.62x39 I had on a cav II lower was the handiest rifle I have ever used.

With the cardinal 16" barrel and cav II lower it was just stupid light with iron sites and a carry handle, IE less that 6# and that was with nothing special. If I had kept on going IE like a alum carrier and a few other odds and ends it would have been close to 5#.

After I started testing the 6.8 110 gr TTSX loads I was not quite where I wanted to be, but it still worked fine. I went to a 20" barrel and wished I had kept the 16 because it became more hassle inside a truck, and front end heavy. I did pick up a few more FPS, but IMO it was not worth the trade. For you hunting bears maybe yes.

It is actually a very underrated cartrige. Anybody that has actually hunted tough animals like hogs with one loaded with tsx bullets knows what it is capible of.

The 85 grain TSX bullets are good too , but too little SD for a bear IMO.
That said they are running those bullets at close to 3000 fps out of 12" barrels I think.

For your bears load up some 110 gr TSX of TTSX bullets for that.
The go to load for the 110 gr TSX bullets is a case full of RL10x. More specifically 29.5 gr but be sure to work up from about 27 or 28.
That 29.5 load was ultra hot in my 11 twist, like the brass was trashed and I would suggest backing off to 29 gr unless you have a DMR chamber and a 13 twist then maybe try it out.

At 29.5 gr I was getting about 2750 fps out of my 20" barrel.

That said I just loaded some 270 weatherby magnum shells with 85 grain TSX bullets I had left over.
Should get about 3800 out of that. Cant wait to try them out on a Hog

FYI, I chronoed the factory 110 gr prohunter load out of my dads 18" mini and got about 2550-2600.

One thing I will say is I am definately going to build a 20" barreld bolt action 6.8 savage one day when I get tired of recoil.

I would also like a TC contender pistol in 6.8.