Just found the original AK thread on AR15.COM. There's a bit more information there. They discuss lots of different parts breakage. It's really not that different than the AR's except for the receiver failures. Bolts, pistons carriers and even barrels have cracked or broken. 
http://www.ar15.com/forums/t_4_64/159106_AK_abuse__home_built_version_update_on_Page_6_.html&page=1
	
		
			
		
		
	
			
			http://www.ar15.com/forums/t_4_64/159106_AK_abuse__home_built_version_update_on_Page_6_.html&page=1
				
		
					
 mini 14, just kidding, not trolling. Honestly, when you look at the ammunition cost vs. cost of the firearm to get 20k down the barrel, it is no big deal to trash the rifle at 20k and start over.