Carbine class malfunction question

[czgunner]

I took a carbine class this weekend. Fired about 400 rounds.
Rifle used was my Colt 6720 which, before the class had about 200 rounds through it. Generously lubed, and bone stock outside of the Magpul handguard, ambi safety, and SSA trigger.
Mags used were Brownells 30 round, with dark grey Magpul followers. Purchase 10 about 3 or 4 years ago. They were new in package before today.
I had 5-6 malfunctions where the round would try to chamber and stop just a smidge out of battery. On finding a dead trigger I would try to clear the malfunction and once had to mortor to extract the round. The rounds looked a bit "bent". Not sure if that is a good description or not. I'm digging through my crap to see if I can find one of the damaged rounds.
My instructor suspected the mags. I isolated one mag, and set it aside, but had one more malfuction with another mag. I used a total of 4 mags in the class.
Ammo used was Wolf GOLD, vintage 3 years ago. Never had an issue with this batch of Wolf before.
Anybody have any ideas?

Here’s a pic of three I was able to find in my bag.