I use the same number of pins as fins, and line em up, either 3 or 4. Simple, works fine. Agree on the CA hardening in blue tube (though I only applied CA once) - I have one 4" BT rocket this way with 3 2-56 screws with > 10 flights, no problems with the holes. The NC is plastic, though a bit thicker than an aerotech NC - no reinforcement/brass sheets used, no problem. Tapping is not necessary, just drill the hole so it takes a bit of effort to push the screws in - you don't want them loose. Ground test. With 25+' of cord, you should have no problem, unless you put a lot of weight in your NC. I did this once on a PML kit (4" patriot) when I first started out with DD: since its a bit short, and I built too aft-heavy, had to add weight to the NC and used the stock cord (10-15'?) - 2 1/16" styrene pins were not enough, 4 were.