Well all rifles are combined in the statistics that are kept and are always single digit percentages as far back as you can go.
The gun people have on them and can conceal is the one available when something happens either criminally or legally. So the bulk of all shootings of other human beings are handguns.
For this same reason handguns were the primary and original target of anti-gun groups, were included in the NFA originally and why there is restrictions on making long guns small enough to fill the void, and if antis were not preoccupied and focused on the subset of firearms they are now likely to return as the thing they wish to ban.
Those that really believe in gun control and reducing the harm posed by firearms through reducing or eliminating their numbers would logicly concentrate on hand guns then.
Before the current focus on assault rifles (and assault weapon is a growing amorphous term that expands and begins to include many firearms that the average person never associated with the term) handguns were the focus going back decades. With Saturday Night Special laws, and other laws intending to greatly restrict them, require extra permits or methods of compliance, or creating requirements intended to increase the minimum cost to something that put them out of the hands of poorer citizens.
The reason for the focus on rifles is they still represent power and pose a larger danger to authorities in body armor during direct confrontation and have some relevance on the modern battlefield. The intent of the 2nd.
Handguns rely on being unseen and used suddenly and unexpectedly to present much danger, which still means they get the ban later.
Handguns and shotguns can be involved in just as deadly of incidents against the average unarmored civilian. Several of our mass shootings involved handguns or shotguns, Virginia tech was a 9mm handgun for example.
But you have to ban what poses a danger to those that would be tasked with disarmament before forced disarmament of other things on a widescale becomes practical. If even a single digit percent of US citizens killed just one person tasked with disarmament you would run out of people willing to be law enforcement.
For an example though I am in no way endorsing or supporting them:
The Taliban have essentially won our longest war in history by constantly killing the law enforcement they view as puppets of a foreign power, though they use truck bombs or offensively going after them at home or their family as much or more than guns in direct conflict to do it. Without the support of the population they do not accomplish a lot even backed by the most powerful nation in the world, and backed by more foreign money than their entire GDP (and quite a bit of their GDP is based on that funding too.) Costing the US over 45 billion a year
https://www.militarytimes.com/news/...on-afghan-war-costing-us-45-billion-per-year/
Trump said they would have to kill 10 million people to win, which is probably a lot of the males of fighting age in the nation, showing just how little of the population supports the US backed security forces.
Restrictions on rifles has nothing to do with statistics, but with power. Civilians having firearms on par with security forces makes them dangerous to security forces. This means the security forces must gain the support of the population to operate effectively.
Civilians having firearms easily defeated makes them primarily only a threat to other civilians which still easily kill eachother with what is legal but allows them to be readily crushed when confronted by authorities, even when the authorities are greatly outnumbered. That allows the authorities to prevail whether they have the support of the civilian population or not. So it does not protect the civilian population from most harm to restrict them, but empowers security forces to do what they want irregardless of what the civilian population wishes.
If you can get people to comply with giving up that which gives them the most power with high compliance and requiring few resources and limited danger then the more challenging task of taking what they are more reluctant to give up later becomes easier because only one side has effective firepower at that point.