Try this one on for size. When I was younger my dad had two British .303s, a Smidt Rubin straight pull rifle rechambered in .308, a 6.5 Carcano and a 30-30 Winchester. Went out to the ranch and I had taken one of the .303s with me. It was one my dad had a scope mounted on and had taken numerous deer and Javelinas.
Well, I reach the blind and climb in and get ready. I pull the zip-lock bag of ammo out and start to load in the .303 magazine.
Hmmmm........Rounds looks kind of shor..dang it.
.308 rounds.
I walked half a mile back to the truck and look thru it for at least one .303 round.
Nope........not one found.......
I grab the Schmidt Rubin out of the back seat from its scabbard and put the .303 back. My dad had gone off with the 30-30.
I make it back to the blind climb in and wait.
About 3 hours later I see the most massive buck I have ever seen. Guessing 150-160 score at a range of about 300 yards. I knew the Swiss rifle was not that accurate past 150 yards from testing.
I sunk low and sulked while I watched him eat to his hearts content the corn I had laid out.
From then on for a few years, I started keeping a small bag that some chewing gum came packaged in tied to the trigger guard. It was a cloth bag from Some "Gold Mine" chewing gum. 4-5 rounds of 30 caliber ammunition fit in it.
Now all my rifles have those elastic rifle shell holders on the stock with 9 rounds. It will not happen again.