Quote Originally Posted by MistWolf View Post
Colt did get it right. When changes made to the system resulted in the extractor spring being overwhelmed, Colt responded and fixed the problem. When the M4 was pushed to its limits in combat (remember, the M4 was originally intended to be used as a PDW for troops in the rear, not for high volume fire) and the extractor once again was overwhelmed, Colt responded with the current spring. Which fixed the problem. However, Colt had a hard time convincing the military to use the new spring because it introduced another part number into the supply system. The military's answer was to use an O ring, a part that flattens & disintegrates from use. Fortunately, Colt finally convinced the military to adopt the new spring and drop the old one from the inventory as the new spring works in all AR configurations. I have first hand experience fixing problematic ARs by simply installing a Colt extractor spring. Before I learned about Colt springs, I had continuing extraction issues, even after installing a new generic spring.

I recommend Colt springs because I have first hand experience using them. I.G. told me that Sionics uses the Sprinco spring and its reliable and durable. I don't have first hand experience with Sprinco springs, but I trust I.G. and am comfortable recommending Sprinco springs as well.

Bottom line: Use a Colt extractor spring.
I have done a ton of experimenting with various small springs. I prefer the Colt ejector spring, and either Ken Elmoor SAW (green) spring, or the Colt extractor spring. Both perform identically, but per SAW/Ken, the SAW spring is better/longer lasting. I have tested corrosion resistance of it, as well as the Sprinco variant, and the Colt, and it does not corrode readily. The Sprinco corrodes very readily, and the colt is in the middle, leaning toward the SAW end of the spectrum. Ejector spring problems manifest with weak "brass dribbling out" symptoms, and can even cause the extractor to hold onto the case long enough that it shoves it into the front of hte port, as the casing is hit by the returning BCG it remained on the bolt face so long, and stove-pipes the gun.