Went to use my BROWNELLS - EXTRACTOR ROD TOOL FOR S&W on my M&P 340. It was loose and sloppy with any reasonable amount of torque on the screw. Figured I must've only ordered the tools for K and L frame, not J frame. Went back to the Brownells site to order the J frame. Discovered that I had ordered the J frame tool; the bigger tool works for K, L and N.
So I had the right tool, and it wasn't working.
Specs say it is meant for 0.228 diameter. Went back to the bench and tried it on a 0.228 gage pin. Perfect. Measured extractor rod: 0.224 inch. Already established that just cranking down on the screw wasn't going to be happy.
Had an idea. Got a strip of aluminum foil. It measured 0.001 inch thick. Two wraps around the ejector rod, work it nice and tight so it doesn't bunch. Tool slides over it, locks down, works perfectly.
Zen and the Art of Smith & Wesson Maintenance.