A little background info first...
FYI, I had no input on the gun chosen. I bought this pistol from my friend's gun shop. I had him order it because my niece was supposed to buy it with Christmas money from her dad. A trip to London for her birthday next month won out in the battle for her money. So I bought it so my buddy didn't have to hold on to it until someone else decided to buy it. My brother said he would buy it from me for her birthday so I will likely only have it long enough to upgrade the trigger and springs for her.
On to the issue...
I shot it today at my brother's place. On the 2nd or 3rd magazine, this happened.
As the box indicates, I was shooting Winchester White Box made in 2010. The ammo has been in a plastic ammo box in my closet the whole time. It blew the block pin and disconnect pin about halfway out of the frame into my thumb (no injuries sustained).
I checked the gun and pushed the pins back in place. I ran another 75-80 rounds through it without issue. I believe that this is an ammo issue but have a nagging thought it could have been an out of battery discharge. A quick search didn't show a pervasive issue with that for this pistol.
Am I thinking correctly or is there something else I should consider?