But guns make it easier. 5 times the murder rate in USA vs England. And England is the home of skinheads and the like who'll glass you in the face for looking at them sideways, so I'd hardly say it can be attributed to English people being more genteel on the whole.
One thing I worked out, is why gun laws are different to drug laws. Reducing drug supply doesn't reduce the demand for drugs, so restrictions don't work. People want to get high no matter what, so they seek it out. Fixing that is another issue however.
But guns work differently. One of the main excuses for needing a gun is that criminals have guns, so you need a gun too. If criminals had less guns, therefore, then the civilian demand for guns would also drop. That's just plain supply and demand. Of course, most illegal guns start life by being stolen from an upstanding citizen who had the gun to protect themselves from criminals with guns in the first place. So more guns means more demand for guns, in a positive reinforcement loop. And with a positive reinforcement loop, reducing the inputs has a greater effect on the outcome than it would otherwise.
Basically, anything that reduces the flow of guns to criminals (background checks, waiting periods, gun training and licensing, regulations on gun storage) will also reduce the demand for purchasing guns somewhat, and will push up the price of illegal guns. A higher price for illegal guns will definitely mean some would-be criminal shooters will be priced out of the market. Again, this is just basic supply and demand logic, and not anything emotional about it. You'd have cases where the shooter couldn't afford or obtain the gun they wanted, and you definitely get edge cases where someone only makes a marginal profit from gun crime. In those cases, a rising black market price means they either wouldn't buy the gun or they'd onsell the gun instead of committing the crime.