I suspect 243 was never the best choice in that circumstance, that's why I also (and originally) have a 270. (130gr Hornady non toxic). It is about matching bullets to rifles (we all did it with lead, why not copper?) calibres to quarry and conditions. I haven't noticed a lot of aversion to buying new rifles by people on this site, probably not many who only have one calibre.Often necessary, especially on the hill.
An important factor in shooting is confidence, I have lost count of the number of people who have told me "Copper is no good, BASC said so". That attitude is not helpful. Right from the start a ban on lead was inevitable. It is time people got past the wingeing stage and worked out what is best for them. I'm not forcing anybody to use a 243, there are plenty of more fashionable calibres available, I am just pointing out that I have made it work for me, it can be done. I thought at one stage of re-barrelling for 6.5 or 7mm but I don't need to there are (factory) non toxic options in 243 that work for what I need.