I just finished up with my second build and I went with the JP 18in. Light contour barrel kit with Lmos bcg and SCS (white spring).   When I took it out for tuning/ barrel break in it took 3 1/2 turns on the adj. screw for the bolt to lock back.  I was expecting a turn and a 1/2 from everything I read.   My question is... Do you think the gas block isn't aligned with the gas port perfectly thus having to back out the screw more to allow more gas to compensate for the misalignment?

Here's some pics with the KMR rail on... If can take the rail off later if you need better pics. Thanks for your help btw

I have always found there isn't a magic recipe when it comes to gas blocks adjustment.

When they are new, there is some break-in that needs to occur, that changes the setting.  The carrier to receiver smooth's out, the spring wears into the receiver extension, the drag from the top of the hammer to the carrier, the tightness of the chamber on how hard brass extraction is, rings on the bolt seating, minute differences in the gas tube chosen, the buffer smoothing out on the circumference to the extension, leakage around gas block to barrel and gas block to gas tube, the type and amount of lube used, the ambient temperature when set.

All these things have impact on the system and some will change over the first 100-200 rounds or so....

I get them running, leave them pretty dry, put at least 100 rounds through them on barrel break-in, and then let it cool, clean and lube well with CLP, and adjust again.

Awesome advice... Everything was brand new.  I'll tune down the gas 2-300 rounds later and see if the bolt locks back.  Btw did you like my ghetto dremel job with my KMR so I could get the alien key in?

Absolutely!  :-)

But, I personally prefer SLR gas blocks which adjust from the front, and don't have the risk of a set-screw falling out.

I was gonna go with the SLR but this came as a kit and the guy I talked to at JP preferred it (go figure haha) over the Syrac b/c you get adjustments inbetween the clicks.  There is a set screw in the front on the low pro adj JP.  I originally wanted the click style.  But the JP was more convieniet and cheaper.  I'm sure they all do the same.

I aligned the gas port with hb industries alignment tool (Great company... Gave me two when I ordered one).  Still takes 3 1/2 turns for the gas block.  But at least I have a piece of mind. Also double checked with two small bubble levels... That method lined up once I knew it was already aligned.  So that's another cheap affective method.




http://i289.photobucket.com/albums/ll232/TheSchraeg/Mobile%20Uploads/6BA1E4E3-9831-49DE-BB06-EDB6F32F9952.jpg