Due to a safety issue there has been a recall of all Ruger Mark IV pistols manufactured before June 1st 2017.  

https://ruger.com/dataProcess/markIVRecall/?r=nav&fbclid=IwAR1gTj-YQXjUEvWtcdESS_qJxn1_SNI_RtBJvAXKHmcD9E_h2jZMbyNGCgo