Years ago I shot a few Winchester factory loads with jacketed bullets in one of my rifles. The few bullets that did hit the target backer were side ways.
I sold the gun, then years later I discovered that the bullets were .376 diameter and I had a .380 groove diameter barrel.
Curiosity was really killing me so I had to try deer hunting with the factory loads.
So now, 4 factory loads remain since I killed a deer with one of them.
I used up 15 of those factory loads, saving the final five for chronograph work (which I still haven't done). mould I slugged the barrel and found it to be .379.