Some random thoughts. There is nothing special or magical about 6.5mm for long range. It just so happens most were made with faster twist barrels to stabilize longer for caliber bullets. Some of the first 6.5’sx54/55etc have been around longer than any of us. Same for the 7mmx57, and some others. Military roots and technology of the day let to heavy bullets being preferred. So with lots of faster twist barrels bullet manufacturers could profitably make heavy for caliber bullets and so it begins. Most 25 and 27 caliber barrels are much slower twist, most are newer designs vs the afore mentioned and made for sporting use. So fewer hi BC bullets are out there, but with a fast twist barrel and hi BC bullets they would be every bit as capable as a 6.5 or 7 way out there ballistically speaking. There are a number of custom bullet makers making these bullets today.
LR shooters imo have largely driven this technology to the point you can get custom barrel twists and hi BC bullets in nearly any caliber now. The 6mm for long range and now 22’s, like the 6mm CM and 224 Valkyrie, give 6.5CM like ballistics with less recoil. They have enough twist to spin 103-108 grain .243 and 90 grain .224 pills. With quicker time to market and lower production costs, pretty much anything can be ordered and shot. One can pick a bullet and order a barrel to shoot it. Good times. For example, I wanted to shoot to 600 for up to elk and be able to kill a Moose closer if I so desired. Ordered a 1 in 9 .284 barrel that happily shoots 140, 145, 160 and 175’s. Could have as easily ordered it in .264 or .308 or...
