Depends on WHAT you want out of the deal.
If you want to give the idea away to better the firearms community, then find out who makes that area of product and pitch it to them.
Granted, some companies get a lot of 'good idea fairies' that want to have some company take all the risk and they want a substantial reward for their flavor of 'faerie dust'.
If you want to get PAID for you idea: Yeah patent SEARCH & application first. See if its out there FIRST and see if you are potentially infringing on someone else's patented idea. (won't stop someone from suing the pants off of you for a potential patent infringement:
LaRue Tactical on the lawsuit with A.R.M.S - The Firearm Blog )
Just because you thought of it and don't see it in the market, doesn't mean someone doesn't own a patent on it (& just haven't brought it to market for various reasons). Or someone can cruise the patent announcements and figure out a way to produce something CLOSE to what you have for cheaper & get it to market faster. (What China is known for with outsourcing production there).
Then, just because you have done a search and have a patent pending, then you still have to find someone to manufacture it, market it and deliver it.
Many folks have ZERO CLUE what it takes to bring a product to market.
Hence the internet is full of dummies that bring down the hate on someone who works their butt off to bring something to market with ignorance like 'patent infringement' - look at the bipod threads on this board for a slew of examples. Just because it mounts to a rifle and has two legs doesn't mean that its a patent-able novel design.
Best of luck, don't mean to be too down on you, but it can be a painful yet rewarding experience!
~Will