Have used the .340 on three elk.. To me it was no more effective in dropping elk than any of my .300's..
I'd point out that the bullet you use is doing ALL the work, and the bullet placement is critical to getting good results. I have used a 340 wby on over a dozen elk, using a 250 grain hornady bullet, but a 300 wby on only two,(200 speer bullet, on one 190 grain hornady on the other.) so I can,t really make a valid judgement call on the difference with so little to compare between the two. As you stated both calibers in both rifles worked, but Ill stick with my 340wby based simply on the consistently good results I've had, neither 30 cal bullet exited , most of the 338 cal did
