I have tried slugs in a side by side, could hit the requisite pie plate at 30 yards. I didn't use it for elk. I have carried a 12 single when going for grouse during elk season. Loaded a slug, figuring I can change the shell when I see the birds, but have an adequate black timber gun ready. Now my preference is a Savage 24 in 30-30 and 20 for that.

When I am really hunting elk, I use a rifle, you want the longer range if needed.

Are they red deer, related to our elk?

Any of you look at the hole a slug makes? There is no reason to think a shotgun won't work.