Years ago I had a Browning SS in 300 wm with BOSS. The 26" barrel seemed to be just a bit awkward so I removed the boss and started again working up loads. No success. None.
So I'm guessing that Browning BOSS rifles are made to shoot with the boss on for best results.
Fast forward to now and I'm still shooting my rebarreled Short action Browning with a 26" #4 stainless barrel in a Browning laminated target stock.
So take off the boss and shoot it. Your mileage may differ.