If it can't handle it why call it a competition revolver? Major is a competition load.S&W makes the 986 a 7 shot L frame in different barrel lengths and The 929 with a 6.5 barrel and the Ruger GP mentioned above.
The 9mm guns require moon clip where the .357 version works with or without the moonclips(at least those that come from the factory cut for moonclips).
I don't really get the distain for moonclips, as mentioned you get your brass back and can load them up at home and spend the time on the range shooting instead of loading magazines.
I don't find them any more difficult to load than loading a magazine and their are tools to help with that just like their are for magazines.
Based on my experience their is no way to shoot 9 Major in these revolvers. Not sure why someone would want/need to shoot major out of a 9mm revolver but their is NO competition that gives a advantage to shooting major in 7 or 8 shot guns against a revolver shooting minor.
Their is a lot more to shooting Major than the strength of the gun. Extraction becomes sticky as the pressures go up and get to the point of hammers and squib rods tapping the cases out a little at a time with the cylinder open.
In the competition world it is actually a bit of a challenge to get minor power factor(125 PF) without sticky extraction and most shooters going to 147 or 160 grain bullets and using certain powders to keep things in check.
Most factory ammo and equivalent reloads should work fine but will almost never makes MINOR power factor out of the revolver.
Since only a couple of places sell 9 Major ammo and it is a small market but I'm sure if you get a response from Ruger it will be NO.
I believe all the manufactures state no reloads in their guns let alone over pressure loads like 9 Major.