Because yelling will make you lose your voice, it’s important to carry a whistle just incase you get in a jam. For example: When I went mountain biking with a group of friends I crashed plenty of times. Luckily, none were serious. However, if I had a bad crash, I would of had to wait until someone pedaled back to me. Unless that is, I could signal them somehow.
To signal for help with a whistle you sound three blasts. Do this in a consistent interval until help comes. The plus side to this whistle is you’ll have a conversation starter when help finally comes.
Step 1: File out a notch
Before you start, clean out the brass with dish soap and cotton swabs. Clean inside and out until the swabs come out completely white.
Grip the shell in a clamp. Make sure to clamp the primer side of the shell or it will collapse. Also if you don’t have a wooded clamp you can improvise to protect from scratching up the brass with something like an old leather belt.
Using a ¼” triangle file, file a notch ¼” down from the taper line on the shell. Make sure to keep the leading edge of the file at 90 degrees. See the pictures. Keep filing until the trail edge of the file is flush with the shell wall.
Remove any burs.