Chamber shoulder and case shoulder gauge for .303?

[Edward Horton]

The AG-42 Ljungman was a gas operated rifle designed from the ground up to use 6.5x55mm lubricated ammunition and the Model 1894, Model 1896 and Model 1938 Mauser type manually operated bolt action rifles did not require lubricated ammunition and were designed to operate without the use of lubricated ammunition.

The key words here are designed to operate “with” or “without” lubricated ammunition and NOT “I think it is OK” to use lubricated ammunition with its increased bolt thrust.

Ag m/42

The Automatgevär m/42 (Ag m/42) (outside of Sweden commonly known as the AG42, AG-42 or Ljungman) is a Swedish semi-automatic rifle in limited use by the Swedish Army from 1942 until the 1960s.

Operation

The Ag m/42 is operated by means of a direct impingement gas system, similar to that of the French MAS-49 and American M16 rifles. The Ag m/42 also uses a tilting breech block like the Tokarev SVT-38 / SVT-40 and FN FAL rifles.

The Ag m/42 uses the 6.5x55mm cartridge loaded into a removable 10-round box magazine. In practice, however, the magazine usually remains attached to the rifle while it is loaded from the top with five-round stripper clips. Like the British Lee-Enfield and Soviet SVT-40, the Ag m/42's magazine was intended to be removed only for cleaning.

Use caution when firing the Ljungman and Hakim rifles as the burn rate of the powder has a dramatic effect on the operation of the rifle. There have been reported cases of catastrophic failures of both these rifles when fired with incorrect ammunition. Even the Swedish m/41 ammunition was required to be lightly oiled by Swedish troops prior to loading as the burn rate of the powder is too slow and the oiling of the cartridge body facilitates extraction.

The main dynamic involves the pressure curve and the timing of the pressure curve as it relates to the location of the gas port in the barrel. While the Hakim has a gas port adjustment the Ljungman does not. As the bullet passes the gas port the gas pressure is channeled back to the bolt carrier to unlock the bolt. With a powder that is too slow a burn rate the bolt carrier opens violently prematurely and at an extremely excessive pressure. This causes the extractor to tear the rim off the cartridge case exposing the action to the dumping of very high pressures which typically exits the action downward into the magazine well, blowing the magazine completely out of the rifle and often destroying the magazine and stock in the process. Close attention must be paid regarding the use of correct ammunition in these two rifles.

Ag m/42 - Wikipedia, the free encyclopedia