It sounds like they were made by C Products LLC. They may be fine or they may not.
Here's my experience with C Products LLC:
I bought 30 C Products mags. I ended up throwing 12 of those in the trash. I have 18 GOOD mags but I PAID for 30.
You really won't know until you put 30 rounds live fire through each one. I have came up with a system I use to check mags prior to live fire that will normally tell you if a mag is okay or not.
Here it is:
1. Visually inspect the mag. Make sure the two body halves were welded together straight and on the same plane. Check all six welds on the front and six on the back to make sure they are intact. Make sure the feed lips are straight. Take the mag apart and check for welding slag and smooth seams inside the mag body.
2. Insert the mag in the mag well. Does it lock in like it is supposed to? Does it drop free when you hit the mag release button.
3. Take a ruler and depress the follower down about five inches or so and see if it snaps back in place or does it bind in the mag body.
This system will normally let you know if a mag is bad without live firing.
Personally the only mags I am now buying are Magpul PMAGs. Yes they cost a little more but they are worth it and I have never had any issues with them.
If I absolutely had to buy aluminum mags I would only buy NHMTG/Okay brand. I have owned a few hundred mags and they are the only aluminum brand I haven't had issues with. They are available here:
44MAG.com-NHMTG