RE: accuracy of semi-auto?
The boss system is an adjustable weight on the barrel to tune the barrel for the load you are using. It's not a muzzle break, you can get it with a break, or without. However the BOSS system is a tunable barrel, not a muzzle break. If you don't want the noise don't get one with the break built in. I don't think that was an option years ago though.
I haven't shot a lot of different centerfire designs, but I have shot enough that I have shot one of each. And I have shot rimfires a lot in all of them. My opinion is it really doesn't matter. Semi Auto, bolt, break action, lever action or whatever they can all be accurate. It has more to do with the build quality and design of the particular gun over all, not the type of action.
I can't imagine a BAR being a piece of crap.
Paul