I have two AICS AT chassis and thought it may be helpful to share a couple of minor mods I have done to adjustable comb / cheek risers.
Users will be aware that to remove the bolt it is necessary to remove the comb.
One of my chassis came equipped with knurled thumb screws which are very user friendly, the other with flush M5 allen screws which require the appropriate allen key.
Searched the 'net, AICS have no stock of original knurled screws and non OEM are difficult to find and stupidly expensive for what they are.
I bought a couple of carbon steel screws about 6mm longer than std screws and two 1.5mm HSS drill bits.
Drilled across the screw heads [across the 5mm deep socket] with a 1.5mm bit.
Then cut the shank portion of the bit to a length which gives about 6mm of shank protruding each side of the socket head, cleaned with contact cleaner and a drop of epoxy into the socket and I had tee bar screws.
Masked the threads and a flash over with cold gal and then black paint and they look like "bought" ones.
Was necessary to centre punch the rim of the socket to get the bit started, on a curved surface the tiny bits walk.
Two finished screws cost under $10.
Comb height adjustment is obviously disturbed whenever the comb is removed.
Given that shooting small groups is helped by not varying anything that does not need varying, I wanted another "tool less" solution.
Near zero cost solution was to set a comfortable height, measure, [allowing for depth of recess in top of chassis beneath comb] and cut a couple of pieces of electrical shrink tube to fit over the vertical posts beneath the comb, this tube shrinks in diameter only when heated and allows the comb to be repeatedly fitted at the correct height.