I like using Acetone and rags or cotton swabs, when it comes to using "White Out".
1) clean off surfaces with Acetone
2) dab the White Out into the lower areas that are stamped or engraved
3) Let things dry for a few minutes
4) Wipe off the high areas/excess with a rag or cotton ball with small amounts of Acetone (don't soak)
5) keep wiping off with minute amounts of Acetone... to much will smear all the lower areas
Like Mrs. Frizzell in the Magic SchoolBus Show, "Discover and make mistakes..." The M14 is a diamond in the rough!
Cheers,
Barney