Firearm frame and barrel assembly, method of assembling and assembly tool

A firearm frame and barrel assembly comprising;

• a frame member having a forwardly open threaded barrel receiving bore, a barrel shroud member having a shroud bore extending therethrough, an axially elongated barrel sleeve member threadably engaged in assembly with said frame member within said barrel receiving bore and having an axially forwardly projecting portion extending from said frame member and into said shroud bore, said barrel sleeve member having a rifled bore extending in an axial direction therethrough and including rifling grooves, said barrel sleeve member having a muzzle portion disposed within and complementing a forward end portion of said shroud bore and terminated by a generally radially disposed and forwardly facing substantially smooth uninterrupted annular muzzle surface surrounding a muzzle end of said rifled bore, said axially forwardly projecting portion being disposed along its entire axial length within said barrel shroud member, retaining means concealed within said shroud bore for securing said barrel shroud member in assembly with said barrel sleeve member and said frame member when said barrel sleeve member is threadably engaged in assembly with said frame member and an assembly tool having an axially elongated tool shank received within and complementing an associated portion of said rifled bore and having radially outwardly projecting spiral lands extending for some axial distance therealong in complementary engagement with said rifling grooves within said rifled bore, arresting means for limiting axial extent of said tool shank into said rifled bore, and means for applying torque to said assembly tool to threadably connect said barrel sleeve member to said frame member, whereby said barrel sleeve member is connected to said frame member with an applied torque of predetermined magnitude.