hunt12ga
This is going to sound crazy and off the wall, but here goes. I am going to suggest you got to a milder 209.
One of the ML I shoot is a Remingt 700ml - plunger gun with an open sided 209 nipple and a very small 'flash hole'. If I use the Fed 209a or the CCI-209M - it will hang fire quite often.... the problem the 209a and the 209m just put out to much gas and debris - it gets clogged up at the flash hole and can not get throught until it looses some pressure. Yet on the other hand if I use a Rem STS or a regular CCI the gun shoots BH great.
So... I am thinking if you clean the BP - you might try a cooler primer and see what might happen.
But... if you are getting a RL breech plug maybe all of your problems will be cured.
Got a request for you to think about.... if Ron's BP works for you, would you send me your old one and let me modify it? Then I will mail it back to you and I would like you to try it and see if it works for you.
thanks - mike