For the non-handloader (or stalkers who handload but must have access to factory ammunition given bans of handloads in some situations on health & safety policy grounds), the 6.5X55 is going to remain the safe option for a long time here and in continental Europe.
As there is only one expanding bullet load available for the 6.5X47 Lapua (Lapua's 140gn Naturalis bullet loading) and given Lapua factory ammo availability / prices, that option is pretty well a non-runner.
That leaves the 260 and 6.5mm Creedmoor amongst common cartridges - same things almost but old and new. Many on this forum might be surprised to learn that the 260, fine cartridge though it is, has at best been a moderate commercial success and is looking distinctly frail now. Winchester, the world's largest sporting cartridge manufacturer has never loaded 260, nor even made brass for it. Remington whose baby it is, has pretty well neglected it recently during the great US ammunition and components shortage period with complaints on Sniper Hide that Rem brass hasn't been made for two or three years and is now unobtainable. What has saved the 260 in the last 10 years and even given it a minor revival is the US sniper and tactical competition shooting scene. The 7mm-08 Rem stole its clothes in the light-recoil medium deerhunting scene with the Remington Seven selling much better in this chambering than in its original 260 form.
Like all highly competitive and fickle competition disciplines, nothing stays static forever, and the 260 is losing out rapidly now in the American 'Tactical' scene to the Creedmoor. What many here don't know is that David Emery of Hornady and Dennis DeMille of Creedmoor Sports USA who dreamed up the Creedmoor 'concept' over dinner at the US National Matches at Camp Perry one evening less than ten years ago saw its purpose as a factory target cartridge available in nearly all US gunshops at affordable prices (which they are by our standards!). It was expected people would handload and that was catered for too, but there was always the intention that has been stuck to that it would be the most widely available and user-friendly 6.5 on the American market and attempt to do what only 223 and 308 was doing, but in a better way than shooting military surplus ammo or commercial copies of standard milspec loadings. One result of that was that most unusually there were no 'hunting' loads made available on launch or for some time afterwards, only the two AMAX loadings (now replaced by ELD-M). A rapid appearance of deerhunting demand for factory ammo seemed to catch Hornady (and other manufacturers) on the back-foot, but the hunter is now big business in the USA for the cartridge. Hornady now has three ELD-X hunting loads and I gather they're selling very well in the recently started deerhunting season.
At the moment, with the bigger factories producing rather pedestrian 260 and no match loads (same for 6.5X55 and 6.5-284), the place to watch what's happening in the US 6.5mm scene is the smaller manufacturers and suppliers - ABM (Applied Ballistics Munitions which has a close Lapua / Berger Bullets tie-up); Cor-Bon; Prime Ammunition, Copper Creek, and increasingly significant in the American retail market as it is now a Cabela's supplier HSM (Hunting Shack Munitions) plus a few others. They all produce (or contract production in Prime's case) 260 Rem ammo now, most do 6.5X55 and a few 6.5-284. HSM lists no fewer than five 260 loadings split between match and hunting.
The question is what happens now vis a vis the Creedmoor and where that eventually leaves the 260 given they're largely doing the same job. Since these are 'boutique' suppliers selling to a niche market that the big boys are ignoring or serving poorly, the Creedmoor actually looks a poor bet on the face of it - after all why would HSM produce five Creedmoor loadings largely duplicating 260 when Winchester, Hornady, Nosler and other large companies are now making this cartridge? Nevertheless, all the signs are that these small producers are adopting the Creedmoor urgently. One negative factor has been 100% reliance on Hornady brass with both supply and QC issues being big turn-offs. Norma is now available but US producers always prefer to buy in-country if possible. New brass suppliers - Alpha Munitions, Peterson Cartridge and others are appearing all over the place in the US and 6.5 Creedmoor brass is in their immediate production schedules alongside 308 Win. Alpha munitions has already negotiated a supply contract with Copper Creek. I'd be amazed if the Lapua linked ABM doesn't announce Creedmoor match ammo at SHOT 2017 with the new Lapua brass appearing.
So .... everything is going the Creedmoor's way right now. It could be that it'll virtually kill the 260 over the next 10 years. Or ... it could be a short-term wonder and be largely forgotten in 10 years time. My opinion, and others can disagree, is that in 10 years time neither extreme option will occur, but that the Creedmoor will still be around, will have better and more options for both factory ammo user and handloader than the 260 which will survive, but maybe into an unhealthy old age fading away like old soldiers are said to do.
But for the British / European 6.5 user who wants factory, 6.5X55 is still the choice for the stalker buying a rifle today that he or she plans to still own in 20 or 30 years time. Even if American factory expanding loads for 6.5X55 gradually disappear (a distinct possibility), Lapua, Sako, Norma, RWS, PPU etc will still be loading it in Europe.
