Hello,

I've installed an upgraded extractor 5-coiled spring like http://www.bravocompanyusa.com/BCM-Extractor-Spring-Uprade-Kit-p/bcm%20extractor%20spring%20upgrade.htm

only the spring and black insert without o-ring! And it looks like the rearward part of extractor is sticking too much from the bolt "surface" because there is a noticeable wear on this end for the extractor:







the rifle was test fired only around 10 shoots so far... Is this normal wear of something wrong with extractor/spring?

Thanks!

Normal. The wear area will become fitted to your bolt group.
The wear shown should be only occurring when there is no round being held against the bolt face. An empty chamber allows the extractor to push out like your photo.

As long as the rifle functions, not an issue.

I'm not a big fan of CS aftermarket extractor springs.

I've never had one of these fail.

http://www.brownells.com/rifle-parts/bolt-parts/extractor-parts/extractor-springs/extractor-spring-assembly-prod4840.aspx?avs|Make_3=AR-15/M4

Nothing wrong with the Colt springs, but on the other hand I have never had a BCM spring fail and I have a fair number in use.

There should be no wear whatsoever on that part of extractor regardless of springs used.

The injection molded extractor in my AIM 9310 BCG is wearing at the same spot. Worse than yours. They are sending me a replacement.