I'm in the same boat. I couldn't find Dura Coat so I decided to experiment with Krylon Fusion on my Glock mag baseplates.
I took two baseplates, cleaned them with alcohol and applied 3 layers of spray bomb. Took two more, sanded as neatly as I could with 200 grit, cleaned with alcohol and sprayed 3 coats. Last pair of plates were also sanded and cleaned with alcohol but this time I used Dupli-color CP199. It's supposed to help paint stick to plastics and prevent chipping.
After a few matches and some trips to the range the first two plates were chipped up and scratched pretty good. The second pair had a few scratches but the only chips were in the logo where I couldn't scratch the plastic with sand paper. The last two were in decent shape, surface scratches but no black showing through the flat tan Krylon.
If I was painting something with lots of nooks and crannies, I would use the CP199 again for sure. If the stock was smooth, I would just sand and paint then touch up the paint every season or two