Yes, you can turn that tap without machine tools, although a tap handle
http://www1.mscdirect.com/CGI/NNSRIT...MT4NO=57572768 will help you keep it straight.
First, however, you need a correctly-sized hole. (20.5mm) What size threads does ACI use on the Maverick? I can't find anything online about it, and the only ACI marker I have is an old F1.
Like the earlier suggestions said, you may need to remove the existing threads and add a sleeve to the gun's body, to actually have material to cut threads into.
Do you have calipers? Measure the threaded hole in the Maverick. While you're at it, if you measure the outside ("Major Diameter") of the barrel's thread, and the distance between threads, we could figure out what thread they use.
Hopefully, the outside diameter of the barrel is smaller than .807", and you'll have plenty of material in the marker for the new threads.
Otherwise...you've got more work.
You don't live anywhere near Virginia, do you?
