seriously anything from a 243 up, in the boiler room will kill the elk, Ive made bad shots with 300 and 338 win mag and yes it helps to have a huge bomb hitting them but they are no magic pill, a 308, 7mm08, 2506, 257 weatherby, roberts, 270, 270wsm, 3006 on up will kill em dead if the bullet hits the heart or both lung, take your time, pass on bad angles and out to 400 yards you will kill em, past 400 yards I would want my 300 rum, 338, 7mm mag long range set up.