Re: 243 or 260 ar
.260 brass is not hard to find. rem and norma, nosler,lapua soon I hear, BUT I use win 7mm-08 ran through my FL die and WHAM, I have .260 brass. I would opt for it before the 6.5CM because I reload. It is a very good cartridge that is very similar to the 260 but since I have a .243 and a .308 I feel .260 is the better choice. I do not use the same brass for all but I could IF I had to. If your not going to reload then everyone will tell you 6.5CM but our local vendors carry .260 match grade ammo. Never shot any (after load development I have only shot 1 load as I feel that is the best way to master your firearm). Both cartridges will serve the same purpose equally. Good luck