Re: The .243. Why many high end mfgrs offer it....
.. Also (in the good to know category) the .243 came out in 1955. So it's a well established round. Whereas, the .260 was marketed by Remington sometime in the late 1990's, (but other versions of it were already around). But as a ".260 Remington" it came to market around 1997 or 1998. Someone else can chime in on that as I'm not too sure exactly when it did come out but either way, the .243 has a longer history.
The fact remains that the .243 is an excellent, precision, LR round that many competitors will continue to use it for years.
I remember not too long ago when the 260 debate was going on. Some thought it was a fad. LOL. I think it's proven itself.