NRA sticker and an American Flag sticker on my bumper. I'm proud of both & don't give a damn who knows it.
Bravo!
My car has two stickers on it. One a small "NRA Life Member" decal. The other advocates the auditing of the Federal Reserve.
There is a second NRA Life Member sticker on a garage door window.
I also wear pro-2nd Amendment shirts often. I try to avoid wearing them to places like the range or a gun store. No sense speaking out when you are only speaking to those who already agree with you.
The time to speak up is when you think you are among some who disagree with you and some who may but are too afraid to speak up. Speak up in those places and maybe you'll find the silent masses, that you think would agree with you, are there ready to add their voice to yours.
I've found that I get the best comments when I am in places where I do not expect to meet people that agree with me. Great examples of comments:
1. The guy at the farmer's market, who I suspected might be a hippy, liked a shirt that stated "Americans clinging to Guns and Bible since 1776;" and
2. The guy who owns a burger stand who my wife thought looked like liberal, started to ask me questions about getting his permit and my range when I was wearing a shirt that said "If guns kill People, then pencils mispell words." My wife was trying to get me to change before I went to pick up lunch, and I was very glad I did not. I also wore this shirt in a University town in Spain and got a bunch of nasty looks.