I had loaded up some bottom of the starting load list using lead SWC in a .38 special to start a guy at work out shooting. Before He & I went out I took my son and daughter to the range and had grabbed the wrong bag of ammo, the rounds I had loaded up for him. My son was shooting the .38s out of a .357. I was talking to my daughter and I heard the .357. make a fstttt sound. When I said that didn't sound good my son said "yah it's been doing that". Turns out there were 6 bullets stuck in the barrel.
So I learned 2 lessons that day, pay attention to what your shooters are doing, even though they are in their 20s and have been shooting for years. Don't load so close to the bottom of the load listing (I may have been just a tad under). I guess there is a 3rd, if you load different levels of ammo make sure you grab the right bag.