No one has ever suggested that all the guns should be grabbed! Even in the UK you can pretty easily get a shotgun.
What your doing is making a false argument as to why nothing should be done.
Then tell us how you would round up all the guns except shotguns? There are already more guns in the US than people, which would make it almost impossible without starting a civil war. The gun culture is too ingrained in the US psyche, as is the idea that Constitutional rights can only be stripped from a person after due process.
You'll get no support from me if your plan is to take away all my rifles and only let me check out a shotgun from a gun club on occasion. And criminals will just laugh at your gun ban while they import guns from elsewhere, assuming the huge supply of guns that already exist in the US ever runs out.
And this whole argument is silly because all long guns combined (shotguns and rifles) account for only a tiny fraction of gun crime and violence. AR-15 rifles are the least of our worries if we really want to put a dent in gun violence.
http://checkyourfact.com/2018/02/20/fact-check-gun-crime-handguns-rifles/
"Handguns were used in 19 times as many murders than rifles were in 2016, according to the UCR data. Handguns killed nine times as many victims as rifles, shotguns, and other guns did combined. The type of firearm used was unknown for about 28 percent of all firearm murders.
Firearms are the most common murder weapon, accounting for over half of the murders each year from 2007 to 2016. The FBI’s UCR shows that 11,004 of the 15,070 murders in 2016 were committed with firearms."
So we need to stop with the whole fear of specific weapons because they are black and scary looking. The idea that certain rifles are too deadly to allow citizens to use is a ridiculous, emotional argument waged by folks who just want an easy answer to this problem. The statistics just don't back it up.