I have guided elk hunters in northwest Colorado since 94' and seen many hundreds of them shot with everything from 243 Win's to 378 Weatherby's and yes a heavy, fast 6.5 caliber like a 26 No's will kill them just fine IF the shot placement is squarely in the vitals. HOWEVER, at least 3 out of every 4 kills I've witnessed you don't have that perfect broadside shot or if you do they're moving and only stop long enough to get the shot off, or they're quartered slightly, etc, etc. When my hunters ask about rifle caliber to bring for the hunt I always tell them 7mm mag or larger firing 160 grain or heavire in 7mm mag, 180 or heavier in the 300's, 225 or heavier in 338's, etc. I personally prefer even heavier for caliber bullets in those calibers mentioned for myself when hunting at medium-long ranges, but those are good minimums to go by for an elk round in my opinion. A fast, heavy 6.5 pill will do the job IF perfectly shot through the vitals of course, but you often don't get that kind of perfect shot and for a man who's paid thousands of dollars to get that one opportunity, a larger caliber simply gives you more options and a much better chance of success if the elk is hit less than perfectly. If you still want terrific speed try a 28 Nosler. I have one that shoots around .15" MOA groups firing 190 Berger's at 3,225 FPS out of it's 28" bartlein 7.5 twist barrel. But to re-iterat: true "every year elk rifles" start at 7mm caliber and go up in bore diameter, not down. Just my opinion after witnessing hundreds of elk kills while guiding.