Has anyone tried to load for a 300 wsm Browning stainless stalker with "boss"?

if you answer is yes at what setting did you adjust the boss to start with?

The deal with the Boss is that you can tune the barrel to a given load. In handloading, we are tuning the load to a given barrel. Reloading for the Boss gives us the opportunity to work the ends toward the middle. (Aren't we lucky?) You can work with one, and then start over and work with the other. Frankly, the barrel will be gone before anything is optimized.

Considering that these are hunting rifles, I would choose Browning's suggestion for caliber Boss setting, optimize the load, and then play with the Boss per instructions IF I weren't satisfied with the resulting accuracy. (Browning will send you instructions with suggested settings if you don't have them.)

BTW, you don't want to burn out a Browning stainless barrel. There is a metallurgical incompatibility between the barrel and receiver, and no one wants to mess with them. IIRC, the threads in the receiver are removed with the old barrel.

I have a friend with BOSSes on two rifles, and he thinks they are way too much work for the result. He just sets them at the factory recommendation and doesn't mess with it. My local gunsmith concurs. You will fire many, many rounds to achieve optimization, which will be different for another load.

LWD

Thanks for taking the time to answer, but those responses are exactly what I told my friend but he still wants to try his hand at it.

Loading for a BOSS equipped rifle can be as easy or as complicated as you want to make it.
What I do is set the BOSS close to the factory setting for a specific bullet weight. I work up loads as I would with any other rifle. Desired velocity at safe pressures is the first thing I look for. When I find a round that has somewhat acceptable accuracy and the desired velocity I am done. Then I load a bunch of these rounds and start the BOSS adjustment process. It takes lot less range time fine tuning the BOSS then it does adjusting OAL, powder charge, primers etc.

For my 300WSM BAR Safari I started with the BOSS at 0 for the 180's and the 165's. 180gr Partitions/ Ramshot Hunter was dialed in at 1.0. I don't use the 165 anymore and I can't find the data off hand, but I do know that the 165's shot very well at 1.0 as well.