If you go down the Maccari route and are putting in an order and have any hint of twang at the end of the cycle get some of his tar as well. I had dreadful twanging with my TX (AA guides can be pretty loose fit), I tried all sorts of grades of moly paste and all eventually loosened up and the twanging came back (a few hundred shots), the tar was much more effective - in the end I've used a combination of that and the heatshrink trick round the base of the guide. Very smooth now.
TX200HC .22, AGS 3-9x40
S410 Classic, Bushnell Banner 3-9x40