I don’t think that’s a fair characterization (I am quite “liberal” but also enjoy shooting occasionally.) But putting that aside, while I think your overall comments are reasonable, you tend to conflate the issues of mass shootings and gun violence (one is a subset of the other.)
With respect to the overall issue of gun violence, you (and other gun owners) also advocate for some of the things we all want (e.g., “prevent access to guns by folks contemplating suicide”) but continually thwart any measures that would do just that because it would make the exchange of firearms very difficult. You use the NIJ report to indicate that certain measures by themselves are ineffective and that there needs to be a comprehensive approach (the main message of the report,) but neglect to discuss the fact that the measures the report recommends are constantly thwarted by the lobbies in support of “gun rights.”
Many of the measures recommended in that report (e.g., Target straw purchasers, Require all gun transfers to occur at an FFL, Gun shows, Gun registration and continuous checks for possession eligibility) are anathema to gun rights proponents, but they are focused on precisely the issue you suggest: accessibility of firearms.
With respect to mass shootings, the NIJ report is clear that certain measures can be particularly effective in reducing or eliminating mass shootings (e.g., Gun buybacks, Large capacity magazines restrictions.) The issue of effectiveness of these techniques is scale. Neither has been implemented on a scale that would be particularly effective.
Again, I applaud your reasonable approach to the debate. However, the unwillingness of the gun owning population to accept any compromise can only lead to continued gridlock and perpetuation of the status quo. The inevitable conclusion of the way things are going will be action in response to a massive tragedy. That will spur outrage and a national movement to eliminate the problem. I don’t think any of us (gun owning or not) want that.