OK, what I'm talking about is making sure the gas holes are lined up perfectly to maximize the efficiency of your gas system and minimize the sort of carbon fouling you showed us photo's of.
Take a measurement of the distance from the shoulder on the barrel to the centre of the gas hole like this;
![[Image: hole_zps224ca6cd.jpg]](http://i906.photobucket.com/albums/ac262/Klemheist/hole_zps224ca6cd.jpg)
It should be at the .300" mark like in the specs drawings for a Lilja;
http://www.riflebarrels.com/products/pdf...4_navy.PDF
Then measure inside your gas block to see if it is the same, 0.300" from the end of the block to the center of the gas block hole. If it is then hard up against the shoulder is where it should be, like the divot is encouraging the block to be. BUT, if the distance in the block is slightly shorter, to take into account the thickness of a handguard cap, then it needs to be slightly forward of the shoulder and that divot is doing you a disservice.
Another way of figuring this out is to push the block back on the barrel hard up against the shoulder. Now spin the block 180degrees. Does the gas hole in the barrel line up perfectly with the center of the grub screw hole?
Take a measurement of the distance from the shoulder on the barrel to the centre of the gas hole like this;
It should be at the .300" mark like in the specs drawings for a Lilja;
http://www.riflebarrels.com/products/pdf...4_navy.PDF
Then measure inside your gas block to see if it is the same, 0.300" from the end of the block to the center of the gas block hole. If it is then hard up against the shoulder is where it should be, like the divot is encouraging the block to be. BUT, if the distance in the block is slightly shorter, to take into account the thickness of a handguard cap, then it needs to be slightly forward of the shoulder and that divot is doing you a disservice.
Another way of figuring this out is to push the block back on the barrel hard up against the shoulder. Now spin the block 180degrees. Does the gas hole in the barrel line up perfectly with the center of the grub screw hole?