You need an angled gun for base. You probably want the 15 ga. Sounds like you are doing a two-piece base where base and cap is one piece and the shoe is the other. Don't do this, do a three-piece base, with separate shoe, cap, and board. The board is just a 1x4. The board does not have to be coped on inside corners, you just **** it. Nail the board into studs through the bottom 1/2" (will be covered by the shoe) and angled downward through the top surface (will be covered by the cap). Use the 15 ga. for this. The board is too stiff to follow bends in the wall, but with a separate shoe and cap it doesn't matter. Now do the cap. Cope the inside corneers and miter the outside corners. Use a dremel with the 543 cutting/shaping wheel to do the coping. The cap will bend to follow the wall, and will hide the nails on top of the board. Nail the cap into studs with your 18 ga. through the skinny part just below the top bump. This can't be seen while standing, so you don't have to be perfect filling the nail holes. Finally do the shoe, bend it to follow the floor. Nail horizontally into the base, this lets the floor move without making gaps in your trim. Horizontal nail holes are also easier to fill. Use the 18 ga. here as well. Again, cope the inside corners and miter the outside corners. Find a place to get small packages of each size of nails that fit your 15 ga., probably 1-1/4, 1-1/2, 1-3/4, 2, and 2-1/2. You will use the 2-1/2 most, but you will find places where you need a specific length, and you will save a lot of trips to the store if you just get them all up front. Do the same with the 18ga. Then when you go through whatever lengths you use the most you can get a large package of those sizes.
