Post by goomba on Feb 27, 2011 19:15:28 GMT -5
The "Tommy's" Thompson
Thompson submachine guns served with British troops during World War II.
By Martin Pegler
2/24/2011
In May 1921, Gen. John Taliaferro Thompson went on a sales tour of Europe, visiting Belgium, Britain, France and Spain to promote his innovative “submachine gun,” a term he coined for the fully automatic .45 ACP that arrived too late for service in World War I. He was invited to demonstrate the Model 1921 at the Royal Small Arms Factory at Enfield on June 30, 1921, which he did with some success. The chief inspector of small arms’ report illustrates his concerns with the accuracy and reliability of the gun. He was particularly puzzled by the requirement for the Blish locking system, albeit couched in faintly impenetrable army technical language.
“There is an element of doubt as to whether the use of the lock is a positive one. The inclination of the sides of the ‘H’ and the corresponding angle of the grooves in the breech block tend to closure, whereas … the inclination of the outside ‘ears’ and the corresponding angle of the grooves in the receiver tend to release. It is well known that with pistol ammunition the inertia weight of the breech block and the resistance of its return spring afford sufficient resistance to hold up the cartridge [case] while the bullet leaves the barrel, provided such weight and spring resistance are correctly worked out.”
In simple terms, the chief inspector was questioning the necessity of the Blish lock, as the counterbalancing weight of the breech-block and its recoil spring, matched to the cartridge performance, should in theory provide sufficient delay on opening when operating on a straightforward, blowback principle. Indeed, the Small Arms staff at Enfield predicted the alteration of the design of later Thompsons by removing the Blish lock completely and then firing the gun remotely under safe conditions. The results were instructive: “The rounds were fired, both ejection and extraction being satisfactory. The gun functioned well and the condition of the spent cases was found to be identical with that of the spent cases … fired with the wedge assembled to the gun.” There was also doubt about the efficacy of the drum magazines: “The 20 round box magazines are much simpler than the drum magazines and appreciably lighter for the same number of rounds, 5 empty box magazines holding 100 rounds in all weighing 2 pounds as against 3 pounds, 2 ounces, for the 100 round drum and 2 pounds, 8 ounces for the 50 round drum. The box magazines are simpler for packing and transport.” There were a few reliability problems when the Thompson was tested, mostly with ammunition failing to fire (not necessarily the gun’s fault) and some ejection problems.
www.americanrifleman.org/articles/the-tommys-thompson/
Thompson submachine guns served with British troops during World War II.
By Martin Pegler
2/24/2011
In May 1921, Gen. John Taliaferro Thompson went on a sales tour of Europe, visiting Belgium, Britain, France and Spain to promote his innovative “submachine gun,” a term he coined for the fully automatic .45 ACP that arrived too late for service in World War I. He was invited to demonstrate the Model 1921 at the Royal Small Arms Factory at Enfield on June 30, 1921, which he did with some success. The chief inspector of small arms’ report illustrates his concerns with the accuracy and reliability of the gun. He was particularly puzzled by the requirement for the Blish locking system, albeit couched in faintly impenetrable army technical language.
“There is an element of doubt as to whether the use of the lock is a positive one. The inclination of the sides of the ‘H’ and the corresponding angle of the grooves in the breech block tend to closure, whereas … the inclination of the outside ‘ears’ and the corresponding angle of the grooves in the receiver tend to release. It is well known that with pistol ammunition the inertia weight of the breech block and the resistance of its return spring afford sufficient resistance to hold up the cartridge [case] while the bullet leaves the barrel, provided such weight and spring resistance are correctly worked out.”
In simple terms, the chief inspector was questioning the necessity of the Blish lock, as the counterbalancing weight of the breech-block and its recoil spring, matched to the cartridge performance, should in theory provide sufficient delay on opening when operating on a straightforward, blowback principle. Indeed, the Small Arms staff at Enfield predicted the alteration of the design of later Thompsons by removing the Blish lock completely and then firing the gun remotely under safe conditions. The results were instructive: “The rounds were fired, both ejection and extraction being satisfactory. The gun functioned well and the condition of the spent cases was found to be identical with that of the spent cases … fired with the wedge assembled to the gun.” There was also doubt about the efficacy of the drum magazines: “The 20 round box magazines are much simpler than the drum magazines and appreciably lighter for the same number of rounds, 5 empty box magazines holding 100 rounds in all weighing 2 pounds as against 3 pounds, 2 ounces, for the 100 round drum and 2 pounds, 8 ounces for the 50 round drum. The box magazines are simpler for packing and transport.” There were a few reliability problems when the Thompson was tested, mostly with ammunition failing to fire (not necessarily the gun’s fault) and some ejection problems.
www.americanrifleman.org/articles/the-tommys-thompson/