Its wear and bedding in not stretch.Nope they do stretch.
And cheap ones especially on ms200 seem to be the worst for.
Check a new one no play in links. Check one you think has stretched and you will find play in each link.
If it was stretch then each link would be longer and no play.




 2 new chains and a cutter bar   that your  going to knack
2 new chains and a cutter bar   that your  going to knack 
		 
 
		 
 
		 
 
		
 
					
				 
 
		 
 
		 
 
		 
 
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 . then I might grind back to size. As other have said keep it sharp, clean, oiled and out of the dirt and a good chain will last ages.
 then I might grind back to size. As other have said keep it sharp, clean, oiled and out of the dirt and a good chain will last ages.