The difference as I understand it, is that machine guns are fully auto, and semi autos are not. I assume you have no problem with fully auto machine guns being banned. Neither do I. I also may differ from you in that I believe that semi autos should be attainable but with restrictions. What restrictions would you accept on any weapons? Cannons? Could a person have an anti-aircraft gun on his lawn if he lived next to an airport?
The second A is one sentence, poorly written in my view. But it introduces well regulated militias as a thing necessary for a free state, then it says in effect that is the way the people's right to bear arms is guaranteed. If instead of a comma after the first clause, the authors had put in "and in addition, the right to bear arms shall not be infringed" or "therefore, through this the right to bear arms shall not be infringed" things would have been different. But the language allows the Supremes to say the amendment applies to individual ownership, but they leave the door open to regulation.
Btw, read a book not too long ago called "Gunfight." It reports that at times, people were *required* to keep a functioning firearm in their house, presumably to fight the Brits if they came back, but also describes western towns as big on gun control. OK corral fight started over a form of gun control, as some towns required visitors to check guns at the livery where the left their horses. Somehow they thought that horny thirsty cowboys and guns didn't work out well. Something in the book to help and hinder both sides' arguments.
French eat snails. Americans eat guns. Not sure I understand the logic of either, but snails do taste better with enough garlic.