Thanks for the comments everyone. The muzzle break is an adjustable "boss" that came stock with this Win mod 70 feather weight. It was a Browning patent and they still have them on some Browning models. By adjusting the Boss you can fine tune barrel vibration and get incredible accuracy from even factory loads. This rifle literally shoots in the same hole at 100 yards! So does my 300. win mag in the same model. They make a lot of noise but (after fine tuning) they are the most accurate out of the box rifle I have ever found. We use ear protection and both of my girls took their deer this year using my .300. It has almost no recoil. They each have their own rifles but prefer to shoot these two because they are so accurate.
