Chef,
.270 with 150s is plenty within 250-yards (Father-In-Law, God Rest his wonderful soul, harvested many elk back home, used a .270, and never lost a one . . . and I'm talking an elk almost every year for a LOT of years!). Glass, glass, then glass some more; know the country. Find elk & the way they are moving, then either stalk, get there early & wait for them, or let "others" haze them your way. Over the 30 years I lived in MT, if I didn't bag my elk during archery season, it was rare when I didn't fill the freezer on opening day and left a bunch of time for guiding & bird hunting. Most folks don't spend nearly enough time scouting & that's the insurance factor. If you don't invest that time, then you're trusting to luck.