I'm working on turning an $80 single shot NEF 12 GA into a minimium length "camp gun".

Currently the bbl and action has an almost case hardened look with no major scratches or dings. I would like to refinish it either in a matte black or parkerized color. The cost of Duracoating is a it too steep for the project. What is a good "at home" coating? I would like to not have to bake the parts in my oven and stink the house up if possible. Thanks.

try Aluma-hyde 2. find it on Brownells.com

rustoleum makes a high heat flat black spray paint for things like grills etc... you can get it home depot for around $10 a can

Among the options:

Do-it-yourself at home Duracoat.  All you need is a cheap airbrush, which they also sell.

Brownell's Aluma-Hyde II.  The II version is non-baking, and fairly tough and durable.

Engine block paint.  Cheap and dries hard.  

In all cases, allow at least a week for the coating to reach full hardness.  Dry doesn't mean fully cured and hard.  

Be careful with absolute flat black paints.  These look great when freshly applied, but many have a bad tendency for the flat paint to wear slightly shiny where you handle the metal and it develops a blotchy look in those areas that looks bad.

Norrell's MolyResin

KG GunKote is amazing when applied correctly, but requires baking.  I did my Kit AK build when you could get spray cans pre-mixed from Brownells, so you might need an airbrush setup now.

I like Brownells Gunkote in an aerosol can. As long as the prep is done right, which needs to be done with any coating, it will go on great and last a long time. The best part about Gunkote in the aerosol can is you can use the gun within a few hours.

I have used it dozens of times and has turned out great. The wear is good as well as one gun I did was carried everyday for about 6 months without any signs of problems.

Use gloves for everything. To keep your skin oils off the parts and to keep potentially harmfull stuff off of you.

Here is what I do:
Disassemble the parts to be coated as completely as you can
Clean and degrease all the parts to be coated the best you can
Media blast all the parts to be coated (I used medium aluminum oxide from Northern Tool)(I have been told sanding will work well also)
Bring a pot of 1/2 gallon water and 1/2 gallon Simple Green to near boil
As the bubbles start to form remove from heat and let it sit for a minute or two to allow the temp to equalize
Place the parts to be coated in the Simple Green solution and let it sit for about 15 minutes
***Do not breath the steam***
Stir the parts occasionally to help break any oils loose
At the same time start boiling some distilled water and turn you oven on its lowest setting
When it starts to boil remove from heat and let it sit for a minute or two to allow the temp to equalize
Remove the parts from the Simple Green solution and place in the distilled water for another 15 minutes
***Do not breath the steam***
Remove the parts from the water and place them in the oven long enough for all the water to evaporate
Remove the parts one at a time, not all at the same time, and coat them according to the instructions

**If you remove them all at the same time and the first ones will be warmer than the last ones causing them to look different**

Make sure you spray outside though because it is some pretty nast stuff, both smelling and bad for you.

After all parts are coated with Gunkote place them back in the oven at the recommended temp for the recommended time. I normally put the parts in then set the temp to the 300 degree temp it requires. Once it gets to temp I time off an hour then turn off the oven and let the parts cool slowly in the oven over the course of a few hours.

Because the finish is already dry when you begin the baking process it doesn't emit any nasty smells in the oven.

This is the down and dirty way I have done it for the last few years and works great. I have only done handguns and small parts but I have went thru at least 4 cans of Gunkote so far. If you have any quesitons feel free to ask.

Dolomite