I think you're right, though it's been awhile since I read the book. I'd actually just recently come across this blog post, covering the Stephen King novel-to-movie adaptations, and in the Misery comparison, the writer mentions:
"Oh, and Annie uses a sledgehammer here instead of an ax, and it's up to you to decide if that's a canny callback to how Kubrick used an ax instead of a mallet in The Shining."

That's what I remember, is The Shining being different, so apparently King's original weapon of choice was changed in two of his stories!