Interesting replies lads, thanks. Well I decided to go for a 22 inch barrel, I'll see how it performs shortly.
The 6.5x55 Swedish round was developed jointly for the Infantry battle rifles of both Sweden & Norway, in the last decade of the 19th Century. It fed the Swedish model M/94 Mauser and for the Norwegians it was used in the Krag–Jørgensen rifle. I believe the main projectile used initially in both rifles for their respective Infantry forces was a very long 156gr. Round Nose of FMJ basic design. For the Swedish Infantry their M94 battle rifles had useable barrel length just over 29 Inches.
Whilst the use of smokeless powders relied on an historically early, limitted choice of slow propellants, used due to the quite heavy for caliber 156gr. round nose projectiles which would have otherwise generated a lot of chamber pressures due to the length of the barrel and the high weight of the bullet.
If one now reloads for this round with bullet weights in the 139gr. upwards, some of the better/best rounds can be produced again using quite slow rifle propellants, and the rounds tend to give of their best from longer than is now accepted from regular factory produced rifles.
The M/94 Swedish Mauser was produced in thousands throughout several decades of service with barrels measuring just a whisker over 29 inches, and this length was considered by the Swedish Military to get the best from their rounds. To get the best VELOCITIES from the heavier for caliber rounds in particular in our modern rifles I believe that length of barrel would still be "ideal" for range work, and for hunting/stalking depending on the barrel thickness and contour and stock materials and design.
That said most MODERN hunting/stalking rifles come from their manufacturers with barrels in the 20-24" and I believe the latter to be a good fit, having sufficient length to get good muzzle velocities whilst perhaps losing a few 10s of f.p.s. from that possible in full length barrels.
When considering a modern hunting/stalking rifle which is to be taken to difficult hilly or mountainous terrains etc. a long barrel is often just impractical due to the rifle's heft. But as long as the firearm is capable of REPEATABLE first bullet accuracy, a barrel length down to 20" and of relatively lite profile should be acceptable, but there WILL BE some penalty in achievable muzzle velocities, especially with bullets in the 130gr. and upwards.
Keeping the ranges from you to critter at sensible distances from the muzzle I doubt whether you or the target will notice any difference, but the arc of flight of the projectile will be more pronounced and that may(?) make the difference to you if trying to down a deer say at several hundred yards.
The choice is yours. My Tikka t3 'Sporter' wears a 24" barrel, but it is a tad heavy and gets heavier if carried for a couple of miles, especially when the countryside is hilly!!
I read latter that you have chosen to get a rifle with a 22" barrel and that should be fine, but check out the muzzle velocity of your chosen hunting round(s) before heading afield, so you will have a good handle on the trajectory arc of your fired bullets!
Me.... When rebarreling becomes a necessity for the return of premium accuracy with my Tikka when using it for rangework, I will be asking for a 28"->30" heavy barrel, perhaps milled with lengthwise grooves to help reduce the obvious weight penalty some...
ATB ..... and shoot safely
