My son uses 30-06 brass necked up to 338-06. I'd recommend annealing before necking up. Will help with longer case life in regard to the necks. Good idea to try to keep a little better track of your cases as to number of firings. Let us know how it works out for you.
Your stock looks good. Did it add much weight to the rifle?
Don't be too hard on Guy. He just did what we all do as in enable others to spend their money:D
Got to the range today to see how Hunter does in this 243. Picture is the best group. Second best was .8 will try the Nosler 100gr PT with Hunter see how it does next time.
I could hunt this load as is.
As for adding weight and effecting balance, I once added some weight to the butt of a Savage heavy barrel 22lr to see how it would react to bench shooting. Even at that it didn't feel right, butt heavy as suspected. For hunting rifle, I wouldn't recommend it.