email away my friend. i want to have a tight fit between the upper amd lower because when i am done i am hoping that with match ammo i can get one moa groups or better. it looks like may of the military and match shooters are using a one in eight twist for the best groups with a wide range of ammo weights. i like the lmt socom stock or a similar magpul stock. do you know anything about the two different gas tube sizes. it looks like there is a point seven five zero or point nine three five dia option.