I would have hoped for better penetration from a 230 gr 338 cal bullet...but it does look like it expanded pretty well at the lower velocity.
My main question is, did it impact the heavy shoulder bone, causing shallower penetration?
If so, it may just add credence to the test results performed years ago by the gunwriters that showed that the only reliable penetration of the heavy elk shoulder bone, is a 338 caliber 250 gr bullet. Elk bone is the densest bone of any animal in north america. Ifyou are going to use less bullet weight, and/or smaller calibers, it is best to stay away from that heavy shoulder bone.
This does not mean that elk cannot be killed with less, just do not expect them to reliably penetrate that heavy shoulder bone and make it into the vitals every single time.
I have had great success on elk, grizzly bear, moose and bison with the 210gr Partition in the 338 Win Mag, and on caribou with the 210 gr Partition in the 338 Federal.
But I must admit that my favourite hunting bullet to date, is the AccuBond! Almost always twice the original diameter expansion, 90-95% weigt retention and great penetration, on game ranging from antelope to bison, in calibers from 6.5 to 375.
As an aside, the SGK in the STW is a great elk load, and is perfectly capable of good penetration. I have taken elk with this combination several times (12+) over the years, from 80 yards to 475 yards, on center chest hits, with penetration from 18" to 30" on broadside and angling shots and/or complete pass throughs. Plus many other big game animals from deer, mountain goat, big horn sheep, to moose. I have taken a black bear with the 215 gr SGK in the 338-06 and am looking forward to taking other big game with it.