What makes the US special? Why does it seem to breed mass killers. There are other countries with similarly high gun ownership per capita, with much less stable economies, with a lot more poverty, and even settler colonial countries which of course tend to be more violent. Yet, you do not see mass shootings like in the US.
The second amendment and the right to have an armed populace has not been historically interpreted as everyone having the right. The actual implementation at the founding of the US and similar countries was for white men in particular. The process of settler colonialism, westward expansion, conquering, and occupation required the deputization of the civilian populace into the genocide of the indigenous population. This same model was again useful for allowing slave owners and their bounty hunters which went on to become the police as we know them today.
The popular responses to mass shootings in the US fall into one of two categories. It's entirely the fault of the guns or it isn't the fault of the guns at all.
It being entirely the fault of the guns is obviously false as mentioned there are other countries with similar gun ownership levels. Banning guns is unlikely the "solve" the issues. However, doing nothing but waiting for "The Big Revolution" is condemning innocent children to die. There seems to be a reflexive tendency to take this rather cruel and heartless line simply because guns are not themselves the root cause.
On a practical level the amount of deaths that can be caused by a gun is simply higher than other legal weapons. But, more notably guns are not viewed as simply tools in the US, but are treated as fetishes in the old sense of the word. They are imbued with a certain cultural power and meaning. A sense of freedom and power deeply rooted in the cultural identity of the country. They are an object of masculinity, conquering, and brutality.
These crimes are inseparable from the guns themselves both practically and ideologically. So, what is to be done? Most of the proposed liberal solutions are to increase the militarization of police, state surveillance, and control over the population. Not really ideal solutions as communists.
I also should briefly address the elephant in the room: "Under no pretext should arms and ammunition be surrendered; any attempts to disarm the people must be stopped, by force if necessary"
I think many marxists falsely (but understandably) mis-attribute this mean an armed civilian populace in the context of the United States. The material context which was being referred to in Marx's writing is very different than a modern violent settler colonial state.
To summarize the question: Are there reforms in the current system of the US which communists could support which would decrease mass tragedies, while understanding that the root causes cannot be fully addressed without a revolution?
We must avoid giving more power to our enemies. Banning a specific kind of gun will likely result in police raiding black and brown communities only. We want to avoid a repeat of the crack/cocaine situation of the 90s.
Ideally responsible adults will still be able to bear arms which is useful as the military, far right, police, and everyone else who thinks we're sub-human also have guns and maybe it's nice if we have a few ourselves.
Some things that might be reasonable reforms.
In almost every mass shootings the person committing the act tends to be 18-19ish years old. In several cases the murderer turns 18, goes to the store buys an AR and like 7 magazines which should probably raise a few flags at the very least. Young men's brains objectively have not finished developing at 18 (which is another reason predatory student loans are so evil) so perhaps increasing the age limit could help. Remembering that reducing the likelyhood while not solving the issue is STILL A GOOD THING. One less 9 year old in a grave is worth a slight inconvenience to hypothetical 18 year olds who have good reasons for buying an AR. Letting kids at 16 drive cars down the highway seems a bit crazy and results in a lot of death, but there's solid reasoning in that it's very challenging to live with any sort of independence in america without a car in many areas.
So, I think increasing the age limit on purchasing a semi-automatic rifle to 25 is perfectly reasonable. They could even carve out separate licenses for pheasant hunters who want a shotgun or whatever. Maybe even a handgun for home protection purposes, but an AR restriction seems likely to help with the situation.
background checks and "gun show loopholes"
This is another point of sale reform so it doesn't involve sending more cops into communities which is nice. Is there a chance that leftists will be flagged during background checks? Almost certainly, but ultimately the state can and will makeup an excuse to attempt to disarm leftists if we ever become a real threat.
The big thing to note is that the people currently most likely to be flagged by background checks are people in colonized communities due to over policing and poverty related crimes. These are also the people most genuinely in need of weapons for self-defence. The other problem is that most of these background checks seemingly wouldn't have actually stopped these privileged white murderers. Quite often the police were perfectly aware and had been warned about the murderer and yet never filed anything or took any actions.
The gun show loophole however seems obvious to close if we are going to have background checks. Gun shows are largely attended by white supremacists and it just seems like a strange failure to enforce existing law sufficiently.
license and test for competence
So this is a weird one because as communists we typically don't really want to give a genocidal and corrupt to the core state any more powers, but yet we agree with stuff like a basic driving test before putting people behind a 2-ton vehicle. Additionally, in many states there are already competency tests for things like concealed carry.
Ideally these tests would be run by people trained on spotting possible mass shooters, but in reality we should assume these trainers will be racially biased, anti-communist, and the whole program itself may very well be simply anti-leftist/anti-black propaganda.
We should of course understand that by trying to solve these problems under our capitalist context we necessarily introduce new contradictions while dialectically working on these issues. I think this one is at least worth thinking about. Perhaps it should only apply to assault riffles and ideally the course would be run by therapists / psychologists rather than cops. The devil is really in the details with this one...
mandatory wait periods
When purchasing a gun you wait a period of time, maybe a month, before acquiring it. I don't really see any downsides. I don't also know if they would be effective? Some of the killers, perhaps most, are ideologically committed to their murderous acts and may well still commit them. Maybe it would have some effect? I could see this being implemented such that democrats can pat themselves on the back and say they've solved mass shootings while nothing actually changes. Regardless, it seems unlikely to have any real downsides so why not?
voluntary buyback programs
The basic idea is an organization is setup which exchanges guns for cash. This has been done a few times, during high inflation there's been "bring us any gun, we'll fill up your gas tank and melt it down".
This is going to primarily target those on the lower economic strata who desperately need the money. It seems unlikely to have any effect on mass shooters and will probably only worsen the ratio of gun owning marginalized communities compared to rich white gun owners.
Perhaps an incentive could be thought of (not money) that will not fall so clearly on class lines and will instead encourage middle and upper middle class people to trade some guns in. This could at least reduce easy access to guns in communities (their kids being able to access extras easily) and combined with other measures could be somewhat useful.
ban assault riffles outright
Any implementation of this would increase policing or create a massive black market for existing assault riffles. Another problem is that the term assault riffle isn't actually a discrete class of gun, but rather a vague concept. A definition of some sort could be written up and then guns will be created to just barely slip under the legal size restrictions or whatever.... gotta love capitalists.
If the existing guns are "grandfathered" in this would be a bit of an issue since they're primarily owned by the far right and petit bourgeoisie as they're the demographic that can afford to buy these kind of guns.
If they're banned that means heavy enforcement with increased policing.
Bump stocks and similar can simply be banned there's no good reason for them.