just a couple of random things...
I had a .930" after market barrel...the first year all three team guns had loosened the receiver mounted sight base... after cantilevering the mounts off the barrel, no further problems
if you start to get a single flyer after dropping the bolt, limit the vertical play of your firing pin (I welded a steel wedge in the firing pin slot)
I added a second mounting lug on the barrel, and bedded the barrel and not the action...stock was a Fajen thumb hole that I whittled a chunk out of so I could hold my head more vertical
a harmonic tuner was added the 5th year and allowed me to "tune" the barrel for the ammo... a 1 1/4" piece of aluminum round stock was bored with a .930 hole... a saw slit lengthwise was cross threaded for a pinch bolt... clamped to the muzzle...shoot 5 shots, move the tuner slightly, and watch the groups change size... off a bench in early no wind morning would put 10 shots on a USPSA paster at 100yd with Win SuperX high velocity
scope was a Tasco World Class AO 6-24x44 with 1/8min clicks and 1/8min dot...anything above 12x you could watch your pulse in
built a fixture to change the depth and angle of the hammer sear notch, and changed the reset plunger to push directly forward on the trigger and not diagonally across... 20oz trigger
I use my CMMG dedicated .22lr upper in an AR for most of my .22 rifle shooting now, so the STC rifle is a safe queen, waiting for the STC to come back to Florida....
edit... I reduced the head space after a long conversation with Mr. David Tubb...