I doubt it will have a measurable impact on anything useful. Even if they got a vote on those bills, Republicans would just shoot them down anyway. Given the hell Republicans have been through so far this cycle, I seriously doubt they fear the attention that comes with a sit-in. Shoot, Republicans would have welcomed a sit-in when Trump was going on racist tirades about his Trump U. case judge.
In addition, if they are willing to completely obstruct a SCOTUS nomination for almost a whole year just because Obama/a Democrat made it, then gun control-related hijinks don't have a chance 
Exactly. Back in 2012, there were a gazillion mass shootings and everyone thought gun control would be a major issue to drive everyone to the polls to give Obama another 2008-style landslide. However, it turns out the issue didn't even make a dent in people's votes.
