Got the M-Carbo trigger spring in and took less than 3 minutes to replace it. Be careful! The replacement spring from M-Carbo is small and I dropped it as soon as I opened it and looked for 10 minutes to find it. That was the longest part of the whole job.
Also some use a screw driver and cross thread the screw into the threads. Don't shortcut it by not removing the trigger assembly as it is easy to cross thread it they say. Mine went fine and even though I thought I wanted a 2 pound trigger I was happy with a 1 pound 6 oz trigger pull.
Let me know how your Mountain Tactical trigger spring does.