when I was planning on a 6.5 I decided on a 6.5 Gibbs, it'll shoot with a 264 winny with less powder and its still a wildcat, thats what I was looking for. That and the fact it'll mirror the trajectory of my 7mm Allen mag to 800 yds.
I'm just starting load developement and I've easily achieved 3200 fps with a 140 gr bullet. just a bit more work to fireform than the 6.5/06, but you get 3-4 grains more powder capacity. the 6.5-284 is an awesome round but seems like every wildcat I ever get becomes legitamised, the gibbs has been a wildcat since the 50's and will most likely stay that way.
pic is L to R of a 6.5 gibbs which split at the shoulder during full power fireforming, a 270 win, a 6.5/06 (essentialy, a 270 necked to 6.5 in preparation of fireforming to 6.5 gibbs) a 139 gr lapua scenar, a loaded 270 win cartridgebeside a 6.5 gibbs
The finished rifle