I wouldn't have said 6.5X55AI is "near identical" to .260 Rem AI. In standard form, the former has a 3 to 4gn water capacity advantage over the .260 which will be maintained when 'improved'. It may even become slightly greater as the Swede has a steeper case taper than .308W based numbers. The .260 is obviously the one to go for for tactical and sniper competition type rifles using short actions and matching detachable box magazines such as the AI design.
In practice, I suspect the standard 6.5X55mm and .260AI have very similar capacity and performance, so it's horses for courses depending on the action employed and rifle type/use, especially now that Lapua brass will become available soon for the former. I've just had a 6.5-284 Savage 12 F-Class rifle rebarrelled to standard 6.5X55 and am in the process or working loads up for it. So far I'm very pleased and a near case-full of Viht N165 is pushing 139gn Scenars out at 2,920 fps in a new (30") barrel in low temperatures around freezing, and also grouping nicely. Right from the off, the cartridge has produced exceptionally small ES values with both 140gn Berger BT Long-Range and 139gn Scenars with N160 and N165, a little less so with N560, so I'm very pleased with it. (As an aside, it is really strange and a bit worrying initially to be working up from starting loads of N160 that exceeded the maximum I used back in the days when I shot Historic Arms with a Swedish M1896 Mauser!)
I had looked at 6.5X55AI. The extra capacity makes it easier to get 140s into the 2,915-2,975 fps range depending on exactly where the sweet spot turns out to lie, but I was put off by the absence of dies. The few people I know using it mostly seem to have Redding bushing sizer and Competition seater dies with calibre sleeves that have been remachined to the new case profile. Sticking to the standard version has let me use an easily obtained body die and Wilson hand types for use in an arbour press, a considerable saving. A long-range BR shooting friend who is very into this class of cartridge has long maintained the 6.5X55AI is probably the 'ideal cartridge' in the calibre having just the right amount of capacity to give 140s 2,950-3,000 fps but with reduced capacity compared to the .284 Win case which he considers overly well endowed in 6.5mm form.
I'm not knocking .260AI. I believe .260 and 6.5X55 and their AI versions are superb cartridges and at last getting the use and recognition that their performance merits. I suspect 6.5X55mm may lose out in the popularity stakes amongst target shooters to .260 partly through short actions, partly fashion, and partly brass issues, but no matter, there will be enough people using it to ensure good quality dies and brass will remain available to see me out, not to mention much younger shooters just adopting 6.5s for the first time!
I've been promised first go at .260 Rem Lapua brass when it arrives with the UK importer Hannam's Reloading Limited and look forward to having a good look at it. If it is like the last three Lapua introductions I've got samples of - .22-250 Rem, .308W Palma and 6.5X47L - I expect the new .260 stuff to be REALLY good. My sample box of .22-250 is exceptionally consistent. There are even one or two cases where I can't find a single thou' variation around the neck and the vast majority are under 0.005", mostly well under.
Laurie,
York, England
