what are the down sides of using plated bullets for match shooting as opposed to lead?
That's a good question but there are so many kinds of "matches" including "fun" matches that it really is an open ended question. There's light rifle, silhouette, falling plates, bowling pins, moving target, rapid fire pistol, bullseye, biathalon, prone, 3p & 4p and the list goes on.....
Sure, all of the "best" ammo is made with lead bullets. I suppose that "most" all plated bullets are higher velocity than standard velocity rounds too. So manufacturers have never really concentrated on making a plated match round. It just wouldn't be taken very seriously.
And I suppose that one reason is because plating will always be applied inconsistently with a variation in thickness. Even if that problem could be overcome, it would increase the cost verses sticking with the plain lead bullet and still, who would buy it?
And more often than not, plated bullets are made as less accurate hollowpoints.
There was one plated bullet that was touted for a long time as being among the most accurate fired from the stock Ruger 10/22's. That was the Winchester Dynapoint [HP] which chronographed as standard velocity or close to it depending on the test gun and batch, old verses new production Dynapoints etc...
Even the new Dynapoints may chronograph at less velocity than the Winchester T-22 target rounds which are loaded slightly hotter than many other standard velocity rounds [in the 1100's FPS range instead of sub-1100 FPS].
So then it's conceivable that for some types of matches, a favored plated round like the Dynapoint may be plenty accurate enough for some shooters.
I can say that I've bought some pretty expensive .22lr ammo. over the years that shot worse than anything I had ever accuracy tested before. I recall some ammo. specifically made for moving target and after testing it in my pistol, its accuracy sure made it seem like my bullseye was moving, but I can attest that the only thing that was moving was the point of the bullet impact!
Like the old adage, in the end it's the shooter that wins the matches. There may never be a plated bulllet to rival a non-plated bullet, but that doesn't mean that it's not possible, and accuracy requirements are always relative depending on the type of match, the guns used and the skill level of the shooters.
Some shooters are just so good that being forced to use a plated bullet may only be a minor handicap.
