Took out my new 69 today for the first time.  Whew!  After about 50 rounds I'd had enough.  Fun as hell to shoot though.  One problem started immediately when shooting WWB 240 grain.  Light primer hits causing failure to fire.  The issue got worse the more shots I fired.  Got it home took off the grips and found the strain screw backed out about two turns.  Snugged it down all the way.  Hope that was the cause.  Should I put a little blue locktite on it?  By the way I had no issues with the Fed American Eagle loads.  I love this gun and would hate to have to send it back.

That strain screw being backed out is probably your problem.  Your next range trip will tell you for sure.  Blue Loctite won't hurt but if you snug it down firmly you probably won't need it.  The Federal ammunition was not a problem because Federal primers are know for being soft.  Some revolver shooters that want the lightest double action trigger pull possible will tune their revolvers down so light that that they only reliable ignite Federal primers.

I would bet with the strain screw tight you will have no issues.

Thanks.  Sets me at ease a little.  I tightened it up but may not have torqued it enough.  It has to be the problem the hammer falls noticeably harder now.

With the strain screw backed out two turns, the action will feel really light.   When I worked in a gunsmith shop, I experimented with strain screw tension.   I found that the most you could turn it out and get 100% ignition is 1/4 turn.

Common on S&W revolvers. Tightening it back up solved your problem. As also pointed out above, with it backed out. Your gun would have felt like the action was tuned lighter. If you liked that feeling and want it back, you can buy a spring kit for it.

Some people will install a lighter main spring in the gun, but you really might get light primer strikes with that. I think that's why Power Custom offered a longer firing pin. You can knock off several pounds of DA pull with a rebound spring change. I believe the factory spring is 15 or 16 pounds. I have found the 13 pound spring to be the sweet spring. Anything lighter and the action would be noticeably slow.

FPNI

That is a gun that begs to be handloaded

10gr UNIQUE 240gr SWC ....you could shoot all day, about 1100fps

Got it back out to the range and it worked flawlessly!  And yes, I do reload for it.  Full magnums out of this gun stop being fun after about three cylinders.  Except the 180 grain XTP's I stuffed with 24 grains of 2400.  Kick not too bad but still give you the concussive noise and fireball I love.

LOL Model 69 and lack of adequate penetration....

nice