I do not think the Mid South bullets are all that fragile. If any thing, they have thick jackets. I have not shot any of the 55 grain, but have the 50 and 34 grain varmint nightmares and have found them to be pretty solid construction, maybe too good for my applications. However, they do shoot well.
Here are two, 5 shot groups at 100 yards shot on different days with the 34 grain Mid South bullet out of a stubbed H&R 22K Hornet
Good Luck and Good Shooting