No I don't full understand America, not sure I fully understand Australia. Having said that not sure anyone "Fully Understands"
I know that there are a lot of uneducated people in America and they are easy to con, the classic sales methods were created in America were a good salesman could sell anything to any one and these under educated people were prime targets.
I would not suggest changing the second amendment, just put it into perspective. At the time of writing the second amendment a gun was a low velocity single shot weapon that had poor accuracy.
They can keep the second amendment, no where in it does it say that you can own a AR-15 or other high powered guns so should not be difficult to ban them. In fact the did for 10 year so that can be done again