Someone a few months back posted a link to an MS260 parts sheet and it had four mini spline choices. I am not sure what is available, and what is available from who you might meet at a parts counter.You can also get standard 3/8 rims to fit the mini spline. 3/8LP and standard 3/8 rims are slightly different.
I might add the smaller chains like the 0.050 1/4 and the 3/8 picco in .043 and .050 are more robust from Stihl than brand x. We seem to be discussing for running on the 42 or so cc essentially 3hp (stock) chainsaws.