I'm going to be following this post,,and hopefully some others will add more info. I just ordered this past week an Ultra Varmint and though I'll be using it mainly for varmints there might come a day when I will want to use it for deer.
I researched the old H&R site pretty close and took some notes and it seems most of the reports on the 243's,,most guns do shoot lighter ammo best, other than a couple guys liking the corelokt 100 and the PMC 100 got a good review. But then there were guys that say 85 grain ammo is plenty for a deer, and most all the guns shoot it well.
I ordered some of the Hornady 58gr varmint ammo and that's what I'll be sighting in with and using unless I run across a great deal on some heavier stuff. I'm not looking to get back into reloading,,but I can't rule it out either.
Keep the 243 info coming guys,,I'm just getting back into shooting/hunting and it's all appreciated.