I have to disagree. The video was silly and DF's post was much better. One can simplify the discussion and leave our relevant information to "prove" any point, both to ban a weapon or to fight against that ban.

I'm not a gun expert. I own a 12 gauge shotgun and a 22. In army basic training I shot an M-16 quite often which is the military equivalent of the AR-15 used in many of these mass shootings. I have some general knowledge about other weapons. Not nearly the amount that DF has, but even with my limited knowledge I could see how this video leaves out relevant information to create a false impression. One can lie very effectively by telling half the truth.

For example the 12 gauge shotgun that totally decimated the watermelon. Its likely that if it had been a human that same shot wouldn't have killed him. Shotguns are designed to shoot birds and small game. A 12 gauge shotgun shell is filled with small BB pellets which create a spread so that if only a few pellets hit the bird it will kill it. Each BB has low  power. Even if all the pellets strike a human in the chest its likely that most will hit a bone in the rib cage and stop there.

Many shotguns can't take a clip. If the shotgun does take a clip a 10 round clip is as large as a 30 round clip on an AR-15. I doubt you could get a 30 round 12 gauge clip but it its available it would be so unwieldy that it would make the gun nearly impossible to use.

In the video its pointed out that one of the high powered rifles doesn't take a clip, but the bullets can be stored in a cylinder running along the barrel of the gun. What they don't say is less than 10 bullets could be stored there.

A lot of the gun control groups don't know what they're talking about when they discuss guns but just as often those who oppose gun control take advantage of that lack of knowledge to post distorted videos like this one. The destructive power of a gun is not simply the size of the bullet. Even the same size bullet can have different destructive power, bullets that fragment in the body or can pierce armor easily, or bullets with explosive charges. A larger bore rifle can be less destructive than a smaller bore if it fires faster and carries more bullets. The amount of kickback can make it hard to aim and fire rapidly. Destructive power is a complex relationship between bullet size, type of bullet, amount of bullets before reloading, trigger speed, kickback, etc.

Most often posts on this subject start with an agenda and choose the information to share to prove that point. I don't have enough knowledge to write a post about the different types of guns and relative destructive power but I do know enough to often spot weaknesses and distortions. DF's post was one of the best I've seen on the technical aspects of guns yet even there I think he left out some relevant information.

As for "trying to buy guns"

To illustrate, a robber should be punished, if they try to breach the fence or enter a pried side window, although they weren't able to finish the job they set out to do, because the alarm was set off, foiling their plan    

If a person who has been adjudicated as being unfit or declared to have forfeited their rights in respects to guns, knowingly tries to breach the safeguards, of a data base containing the names, of those who are to be denied access to guns; they are just as guilty of trying to foil or find a gap in the fence or an open window of opportunity.  

The alarm went off; they knew they were not to enter, as they attempted to take an action prohibited

Just like leaving fingerprints at the scene; you may not have been caught immediately, but with a good investigation, the culprit is apprehended.

They'll think twice before attempting another violation or condition placed upon them 

77,000 felons or those deprived of the "right to bear arms" taken off the streets, would go a long ways in bringing security, to law abiding citizens.