06-12-2012, 07:03 PM
It is not abnormal for a semi auto to make marks on the brass during cycling. To prove a point lock the bolt back, stick your finger in the ejection port and drop the bolt. As you can see the case is subjected to violent movement, so anything it hits will leave a mark like on your finger. You may be able to find the source by putting a line on the case head and orient the cartridge in the mag so it faces up. Cycle it through and since you know how it was sitting you should be able to tell what it struck. Then you can polish the place with some crocus cloth until there is no more marks on the case. Check out this page for what areas to clean-up http://www.snipershide.com/forum/ubbthre...er=1944031 If the case was only cycled by hand the gas block should not have any effect.