Grandpa had a 260 growing up I wish I had it now
here is some info from Norma's site
260 Remington
This is simply the 308 Winchester case necked down to handle 0.264-inch (6.5mm) bullets, with no other changes. This was originally a wildcat, most likely dating to shortly after commercialization of the 308 Winchester, in 1952. Ken Waters and Jim Carmichel are some of the better-known pioneers of this chambering. In 1997, it became a factory offering, under the moniker 260 Remington. (In fairness, we must mention that A-Square, now defunct, had already standardized this chambering, as the 6.5-08 – the Remington moniker therefore seems rather unfair to A-Square.)
The 260 Remington has about 5% less usable case capacity than does the 6.5x55 but is generally loaded to higher pressure. Accordingly, it essentially duplicates performance of that, circa 1894, Scandinavian chambering, while working properly in short-action rifles.
Magazine length of such guns usually limits overall cartridge length. Therefore, with heavier bullets, cartridge overall length limitations require deep seating and performance suffers. Nevertheless, the 260 is a tempting option for use in a lightweight "mountain" rifle. It has adequate performance for anything up to and including medium-sized big game at normal hunting ranges.
The 260 is somewhat light for use on species such as elk and moose. It just manages to meet the legal requirements to qualify as a moose cartridge in Sweden, provided that one uses handloaded cartridges with best bullets and propellants (often with a compressed charge).
