I think it is 3.0,but you can get the settings for the boss on the browning web site.
I have a 7 mag and a 300 wsm in the browning stalker with boss,but if I ever buy another browning it won't have a boss on it.
As far as recoil the boss on the 7 mag really helps but on the 300wsm it still kicks pretty good to me.
I made the mistake of shooting the 300 the first time with out hearing protection but won't make it again I hope.It not only made my ears ring it really hurt.
I shot a few groups taking the boss off with the 300 and my tiny groups went too.These were with reloads don't know about factory loads.