How do you determine this?

You said you had three of these incidents in the last 1-1/2 years, that sounds more like a firearm problem than an ammunition problem at first glance. Many shooters never see this type of event, or maybe only one or two in their lives. You're seeing it very frequently (relatively speaking), and with different types/brands of ammo, all in the same gun.

I wonder if somehow your ammo could be getting contaminated with oils, moisture, etc. Causing the powder to have a slower burn rate than it should. Could that cause something like you are suggesting with "bullet still in the barrel when action starts to open"? I don't know. Just speculating, based on the fact that you're having so many of these failures. It's either got to be the gun, or some common defect in the ammo, possibly brought on by the environment you're storing the ammo in.