I bought one of the BW5 FS guns and it came with the new gold extractor. When I got it I went out and tried it out and was saddened to find that about 3 round out of every mag would not eject properly. This was consistent with both 115 grain and 124 grain ammunition and with both the mag they sent me and some factory HK mags.
I could have sent it back to Bobcat to have them fix it but instead I filed for an SBR and stuck it back in the gun safe. 2 months later (nicely done BATFE! Fastest SBR I've ever had) I was approved for an SBR so I replaced the trigger pack, the bolt carrier, and the bolt head with factory German parts and tried it again. This time every thing went flawlessly and I haven't had a single problem since. I've fired probably 500 rounds through it since I got it.