You can probably cut a 1/2in off the composit stock but you'll need a new pad fitted to it. A muzzel brake simply is a screw on item that reduces recoil. However it does involve threading the barrel to install it. I know you probably don't have the tools to take on these tasks. Take your rifle to a licensed gunsmith to have them do the work to the stock. Have the gunsmith send the barreled action to Mag-naport to have them install their Mag-na brake. The cost of cutting the stock plus fitting a new pachmayr pad will run around $50.00, sending the rifle to Mag-naport for their muzzel brake will run around $250.00 Thats a total of $300.00, but it's worth every penny when put into a high quality rifle like the Ruger M77.