I appreciate and respect your opinion and I agree that someone, no matter the age, that is hell bent on committing a crime will do whatever it takes to accomplish that goal. But I find it hard to believe that changing the law to buy a rifle to 21 or having some type of co-signer wouldn't at least prevent or deter one person thats on the brink of committing such an act from actually doing it. Notice I said on the brink and not hell bent.

Your comment about texting is similar to the point I made in an article I wrote a couple of weeks ago....
"Approximately every 2 minutes someone is injured in the United States in an alcohol related car crash.
Every day, almost 29 people in the U.S. die in alcohol related crashes. That's one person every 50 minutes; according to NHTSA in 2016
Also according to NHTSA statistics. In 2010, the most recent year for which cost data is available, these deaths and damages contributed to a cost of 44 BILLION dollars per year!"

"Those alcohol related crash statistics are overwhelming, don't you think? But yet I don't see people on the news lobbying for alcohol control, car control or anything else related. Why is that? Is it because money and politics is more associated with guns?"

So yeah, I get that there's people dying from more things than guns that you don't hear about every day. And yes, there are politicians that want to see total control and every gun taken off of every citizen. But I don't think that changing the age restriction to buy certain weapons is all about control, I think it's just adapting with the times.

How many people died from texting drivers before they made it against the law to text while driving?

Same thing here man. How many more school shootings or mass shootings in general is society going to put up with before a change is made? As I said in my post, I don't want to see new laws or weapon restrictions either but it seems like the age limit change is the most reasonable and sensible thing to amend. But if we don't "try" to at least do something to fix the problem and the shootings just keep getting worse, I got a feeling that our next administration will be much more assertive on actual gun control instead of just amending an existing law. Just my 0.02