@MistWolf, I'm not saying you're wrong or colt spring is bad. Just my thoughts here.
If I recall correctly BCM spring was created for or based on SOCOM MK18 design. Might be 100% wrong here. Bad batch of springs can also be a problem. Personally, I don't put too much faith in Colt extractor spring simply because they had at least 5-6 different design iterations over the last 50 years and couldn't get it right first, second, or third time. It took them 50 years to get it right... maybe. Or maybe they'll get it "right" the next time.