"My 20" is smoother and seems to cycle faster"
I just tried out the recoil springs you sent me. Going heavier was counter intuitive to me. On a pistol the recoil impulse is usually better with a lighter spring. Not so with the rifle. My 20" is smoother and seems to cycle faster. It locked back on the last round with lighter ammo just fine. Thank You! I'm using the standard weight bolt carrier with the light buffer. The sights track reliably off hand and barely move in a prone position. I like it...
I replaced my US Optics mount with yours. I was doing fine with the U.S. mount till the rifle fell off the bench before the R&R match in Oregon. I found out on the first stage that my zero shifted. Part of the problem is that I have to hang the mount off the front off the gun compromising it's original design.
"I still put my nose on the carry handle. "
With your mount I'm still one notch out over the front but I'm not concerned about the mount moving at all. It is 5mm higher than the US but I can get to that. Very clean mount! I'm going to get a few more.