What makes you think that?
If I had to guess, I'd say ~30-40% of people on HN support the US concept of "gun rights". "Gun rights" support probably around 50% in support in the US, but 80-90% against outside the US. Given the large international audience HN has I think that would move the average significantly.
(I agree with the rest of your comment, though)
 http://www.cbc.ca/news/world/story/2012/07/23/gun-control-po... says in the US 44% support the status quo and 11% support less strict laws.
A solid majority don't know what the laws are so "support the status quo" is interesting.
They tend to believe that the laws are less restrictive than they actually are. When you quiz them about specific "proposals", which happen to be current law, you find that those proposals are significantly less popular than the status quo.
Two examples of this are wrt concealed carry and automatic weapons. On the former, very few people think that police should have complete and arbitrary discretion wrt CCW, yet they do in the jurisdictions with the majority of the population.
They're not a very acccurate reflection. For one, their demographics are very different.
> then that would reduce support on HN even further than I estimate above.
Reduce support for what? My claim suggests that the more folks know about US gun laws, the less they support current law and the more they support less strict laws, and I didn't even address the folks who want more strict gun laws. (When you ask them the same questions, many of them have the same reaction as "status quo" folk. They want "more", but they don't want things as strict as they already are.)
BTW - That's why the whole "assault weapon" campaign is political genius. The guns in question are "military" in the same sense that the cars that you can get at a Chevy dealer are race cars (that is, not at all). It plays on ignorance.
Then again, a large number of folks think that "tactical vest" means "bullet proof". (It means "lots of pockets"; think fishing vest, only black or camo fabric.)
BUT - I think that technology is an amplifier - it makes things easier, quicker and more powerful than before.
Sometimes, building tools that amplify certain behaviours isn't neutral.