I called H&R 2 days ago and asked them if ALL 243's had the same twist rate. According to them, all 243's have a twist rate of 1/10. I would disagree. I bought my 243 about 1 year ago. At that tine it was called a "Handi Ultra" and is stamped on the barrel "Ultra". I do not remember there being a "Ultra Hunter" and "Ultra Varmit" available ( of course I could be having senior moments :-) ). The rifle has the lam. stock and the bull barrel. After trying to shoot 100 grain factory ammo with no success (bullets would keyhole) I checked the twist rate and it came up 1/12, thinking I screwed up, I had a friend check it. Same results. I called the factory last year and got the same answer- 1/10.
H&R offered to checkout the barrel, but the thing shoots 80 grain stuff so great I will live with the lighter ammo. It is hard to argue with success and I get 3 round groups with all rounds touching at 110 yards. If I send it back, I don't know what I will get, plus it has a great trigger pull, which might change.
I guess I got a little long winded, but I hope this helped.