It's sort of like Christians.
A whole lot of people call themselves Christians. Maybe go to church 2, 5, 10 times a year and that it.
And then there are the Tea Party type Christians, the hardcore, Bible-thumping, Jesus-jumping folks who constitute a bloc which is effective.
The basic gunowner is not a force, doesn't contribute money to antigun movements,isn't active. The NRA is like the fundamental Christians, active and involved.
You can't really count the non-NRA gun people as a lobby.