Re: 260 performance in shorter barrels
My shooting partner just had a .260 built with a Krieger 4 groove 8 twist tube, cut and crowned at 20". Chamber was done with a PT&G match reamer with .060 freebore and .297 neck.
Berger 140 gr VLD behind RL17 near or just above max, Rem brass, CCI 200 primers .005 in the lands, 2650 fps and .25 MOA.....
I had mine cut crowned at 26" with a Krieger 5R 8 twist, same chamber and will be running the same projectiles. The barrelled action just got back from the smith yesterday. Need to do all the finish work, painting, bedding, etc, then work up a load for it. Once it's all dialed in I plan to have it cut to 24", then 22" and dependant on velocity, 20"... I was unable to find solid data for the .260 in regards to barrel length so I figured I would come up with my own.