Upto about 50M you probably wouldn't notice much difference, but for the purposes of DMR and Sniper with longer engagements sensitivity of BB / barrel contact increase a lot!
Proof in sniper testing with a BASR @ 500fps, swapping to longer than even 303mm hurt accuracy in a big way at 75M and beyond.
We were getting accurate measured shots to torso size target at 100M with a 303mm!
In the same vein, tighter bores increase this sensitivity again.
The above bolty was running a 6.05. 6.03 is the smallest I'd go on any RIF other than a pistol.
Best
Dave