That does it! I'm
BUYING a S&W M&P 10 just as soon as my budget allows!
All this talk about not buying one simply based on this one problem that one person is having is silly. Make that choice if you choose...it's certainly each individual's choice.
However, it might behoove all who do make that choice to actually check these EXACT circumstances with any other manufacturer they might consider buying this rifle from.
Let's talk about this "proprietary" issue people seem to have a hard spot with:
Since the 308 was never adopted by the military, it would seem that there was no push for standardization across the board. Which means that just about every maker that manufactures this is going to be at least partially proprietary about it, so don't expect the component interchangeability that people have come to enjoy with the AR-15 platform.
And before anybody brings up the SR-25...it's not interchangeable with all the other AR-10 platforms, either, even though it's somewhat based on the AR-10.
If people want more interchangeability with an AR-10, then they need to research their choices appropriately. If they want certain proprietary components to be available, then they also need to research this appropriately.
Now, having looked at the cost of an M&P 15 upper vs the cost of an M&P rifle, I'm not all that sure that it wouldn't be more cost effective and simpler just to buy a whole new AR-10, complete with warranty, even IF an AR-10 upper were available from S&W in the first place.
If I were the OP, having destroyed my rifle barrel in this manner, I'd very likely simply retire the rifle to a safe as a show piece and see if the future brings about the proprietary parts availability required to fix it. Alternatively, I'd look into putting the various other components up for sale to people who might need to repair other parts on their own M&P 10.
And then I'd go shopping for a replacement.