I have to disagree.
I have witnessed several good shots made on cow elk with frangible bullets and the cow was on the move! One was a shot from a .243 with a SGK, another was from a 7-08 with a SGK. Both hit the boiler room and shredded at the ribs. The youngster with the .243 hit the cow three times in a matter of 2 hours and you could have covered the three round group with a dollar bill. The last shot got a fragment into the heart and he harvested his first elk.
Bullets are designed for a specific purpose, medium game are not near as solid as large heavy game. Elk can be BIG.
Please, do not hear me say Sierra makes poor bullets. Quite the opposite is true, they are masters at their craft. Light weight SGK bullets are not designed for heavy game. Keep in mind, all bullets have a range of velocities they are optimized for. I have observed solid hits on elk at stupid yardages and the bullet did not perform as the hunter would have liked because the bullet was traveling too slowly. If you have questions, ask them about their bullets and what your plans are, they will be happy to make a recommendation.
CW
I asked sierra about a better bullet for elk for the 7mmBR, they told me it was light, but they don't make anything bigger for pistol velocities. In fact they don't make that bullet anymore.
If you want to say that elk are hard to kill and BIG, why start with a 243? You did not mention what weight bullet in the 243, so I am guessing it was on the lighter side. My experience with Sierra bullets is that they do not stand up to bone well, regardless of whether it is whitetails, or elk. A rib exploding a bullet, must be a VERY lightly constructed bullet, the ribs are only about 1/2" thick or less and about 1.25" wide, hardly heavy bone.
I shoot elk mostly with a bow, but I have killed them with a 270 winchester with sierra 130's, 7mmBR with 130's at 2200fps or so, 405 winchester with slow cast bullet, 45-70 with slow cast bullet, 475 wildey 400gr going maybe 1000fps, 300wsm, and probably some others that I don't recall. I have never had one go any distance after being shot.
The 270 with 130's put one through the chest, it exited leaving a 1" exit hole, the next round went within 2 inches of the first, he never moved other than falling over, that was at 40 yards. One of the 7mmBR elk was at 360 yards, it went maybe 60 yards, the bullet exited. The farthest an elk traveled after being hit with the 7BR was about 100 yards, it was a 200 yard shot that removed the top of the heart, I recovered the poor performing bullet. It was bent in the shape of a banana. The 405 punched perfectly through the heart, it went maybe 50 yards.
I have killed many elk myself and have "guided" many friends, with a total of dead elk probably around 60 or 70. I have only seen one elk take multiple "good" hits and keep going. That was with a 338.
An average cow rocky mountain elk is going to go about 400 to 450, an average raghorn maybe 500 to 550. It takes an older bull to get over the 700 mark, the stories of 1000 pound bulls are just that, bull, unless you are talking about 380 class bulls and up.
I will take a 270 for elk anytime. I have a moose hunt next week, I would use the 270 for that, but I'm taking a lever gun.
No offense intended, just offering up my opinion.
