Well, no, the racially challenged individuals apart of gangs in LA and other cities, I am sure, support gun rights.
Also, again, the constitution was written in the 1700's. Issues back then are irrelevant to issues we have today, therefore, it should be re-written.
Gang members don't care about gun rights because they get their guns illegally anyway. More restrictive gun laws would not stop them from acquiring weapons and committing crimes with them.
Example: Chicago has some of the strictest gun laws in the country, but one of the highest gun violence rates in the country. Gun laws are largely ineffective at preventing crime. In areas with strict gun laws and low crime rates, the statistic is often explained by other means, such as the societal values and culture of the area.
For instance, Japan has very low gun crime rates, but it also has very low crime rates across the board. On the other hand, Britain has very restrictive gun laws, and low gun crime rates, but a very high crime rate across the board. The most popular weapon in Britain is the knife. Their culture is far more similar to ours than ours is to Japan, and clearly their strict gun laws have not significantly lowered crime. If Japan were to loosen their gun laws considerably, I think we would see a rather negligible increase in crime, or none at all. Criminal activity is simply not prevalent in Japanese culture.
To your second point: It is true that the values reflected in the constitution are not entirely relevant today. That does not mean they are not applicable whatsoever, and that does not mean the constitution needs to be entirely rewritten. Most of the points in the constitution do still apply today, regardless. While it could probably use a revision, a complete rewriting is unnecessary, I think.
P.S. Thank you Allasphore. It's difficult to argue coherently with my back up against a wall.