I chambered up a 6.5x68S on a 6.5x55 Model 38 1945 IIRC & yes the action is a little short) This one had a decent barrel, but it was .266" groove to groove and I think standeard 23.4" long or was it 24.3"?

Using a slightly reduced (from my buddies 6.5x68 load) load of H870, I was able to drive 129gr. Hornady SP at a respectable 3,200fps. This load gave me 1 1/2" groups at 100 meters with a 3-9x32 scope.

The only animals I shot with this rifle were 2 snowshoes hares, 1st at 200 yards, second at 210yards - with the same bullet/shot - a double kill. They were perfectly in line on the road ahead of Keith's stopped truck. I said to Keith my hunting buddy - 2 for one? He said "lets see it". "POW"!

We paced it off and and revealing the bullet which actually appeared not to expand initially, went through both shoulders of the first bunny (standing) making a 1" hole, both sides, hit and bounced off the road 1/2 way to the second then fragmenting and took the second with possible bullet fragments and stones from the road. He was peppered along one side. They had been crouched, facing opposite directions.

Yeah - good round!

I spotted (25x Spotting Scope) Keith on a bull calf elk down in elkford in the 1980's using his 6.5x68 Model 1917 Enfield. 1st round through the lights - 250yards. Lung tissue flew out both entrance and exit wounds. ALL of the elk ran 30 yards and stopped, milling around. When the target calf was clear, the second shot - same placement - perfect lung shot.
Again, bloody-tissue and liquid out both entrance hole and exit. Again the elk ran 20 to 30 yards and stopped. The calk hung his head down, then dropped. Sometimes they just don't know they are dead. Elk can be tough.
This was a late December special draw hunt.

The little 250 pounder (dressed) had a 5" hole through & through both sides. No shoulder muscle/meat damage, just rib meat- about 8" diameter - both sides. He was a decent size for a calf - with 2 1/2" high, hair covered "protrubences" for horns.

Keith was driving the 129's at 3,300fps from a 24" bl. using H870.