Mitchell-
I've got the UV .243 and I really like it with 55-85 gr. loads. 'Mine' will not shoot anything over 85 gr. w/o keyholing!? I sometimes wish I had the standard barell as this thing is heavy in my book. But, as others have said it does get hot. Between 5-10 shots on my heavy barell and it is hot. Good luck with either of your choices. 243 is a really good caliber, I know I have a blast with it. It is also a very fast caliber, so either barell length will still be smokin. BuzzKill