.50 would be a terrible idea, especially for a beginner. The cost alone for ammo is prohibitive, not to mention finding it. In this state, that rifle is a lame duck. The recoil would basically make it hard for you to learn to become a good shooter, it would annoy the hell out of anyone next to you on the range (if the range even allowed it due to noise pollution), you might get kicked out for busting up their metal targets, you'd shoot it 10x before your shoulder hurt, plus you'd be out of money, plus your friends would shoot it 1x and then refuse to come with you. Plus it weights a ton. But you'd look cool.
A .308 or even a .223 bolt action is the way to go. Ammo is available everywhere, in every gun store and even sporting stores. It isn't horribly expensive. The recoil is nothing. It won't annoy people at the range, plus all rifle ranges will allow it. It won't bust up the metal targets. Your friends will enjoy shooting it. And you won't look like an idiot shooting your .50 at 100 yards.
A year ago, I was with my .308 LTR shooting at the 100 yard range. Bunch of guys showed up with a .50 Barrett. They put a short log out at 100 yards standing vertical and put some clays on it. They then spent the next 30 minutes shooting at it and hooting and hollering. I had no idea what they were shooting at, as none of the clays broke on the log, and the log didn't fall over. So finally after about an hour I went over (kindly declined offer to shoot the .50, possibly killing someone two miles away while possibly detaching my retina), and asked what they were shooting at. They told me they were shooting at the log but "the bullets are soooo big and sooo fast they are passing through the log".
I almost died inside.
So I told them that wasn't possible (having shot many things made of wood before, but I won't incriminate myself). They insisted it was hitting the log and passing through because "it is soooo powerful." I told them to hold on a minute, 1 shot. I walked over to my .308, aimed at a clay on the log, shot it, broke the clay, and the log tipped over.
Most likely with the down angle on the rail and god knows how they had scope set up (cheapo scope, which was hilarious on an 8K gun), those rounds were over the berm. And just flying out to god knows where behind the range, luckily all wooded (except for that occasional house).
Not saying .50 isn't awesome, but that is more of an expert's tool, something you get after years of shooting, and something you don't expect to shoot much, or perhaps not at all. And not something that makes sense in MA. Even if you lived in AZ or someplace, I'd tell you to get a .338 because that is far more useful and affordable, and basically does everything you need. Do not get a .338 here, you will be wasting your money.