Today’s rifle is an curious example of forgotten weapons going full-circle and being reinvented. What we’re looking at is the “44 Bore”, a colloquial name given to AK-pattern rifles rechambered for the German 7.92×33 Kurz cartridge in Pakistan. How his cartridge came to be popular in the tribal areas of Pakistan seems to be unknown – according to Muhammad Yasin of the Punjab Forensic Science Agency, the Pathan tribes claim the cartridge as an indigenous development (and are quite proud of it). The name, however, appears to come either form the StG44 rifle designation (in which the 7.92x33K cartridge was originally used) or from British 7.62mm NATO cartridge cases headstamped “L44A2” which were commonly reformed into 7.92×33 dimensions.
The original of its name aside, what makes this type of rifle interesting is that it can chamber and fire both 7.92x33K ammunition and standard 7.62x39mm ammunition. This is done with minimal modification to the guns, too. The bore diameter is left unchanged – 7.92mm projectiles are simply squeezed down to 7.62mm upon firing. This increases pressures, but not so much as to create a critical problem (it probably causes stretched headspace in the guns over time, but these guns are not well cared for in the first place).
The chambers are reamed to accept the 7.92×33 cartridge, which is short enough that doing so still leaves enough intact chamber around the case mouth to headspace (more or less) a 7.62×39 cartridge. This leaves the rear end of the chamber larger than the 7.62×39 case (11.95mm vs 11.3mm), but the case head is held in place by the bolt face. Would this be considered safe in US or European shooting circles? I doubt it – but as Weaponsman described yesterday, [tribal Pakistan] Is A Different Place.
The closest comparison I can think of to this type of rechambering over here is a relatively similar technique used to rechamber .303 barrels for 7.62x54R. More than a few owners of Bren and Vickers guns (myself included, actually) wanted a way to use the cheap and available surplus 54R ammo in their guns instead of the much more scarce and expensive .303 – 54R is an idea substitute since they are both .311 bore diameter and both rimmed cases. The easy way to make the conversion is to run a 7.62x54R reamer into a .303 chamber. Both rounds headspace on the rim, so that is not a problem, but 7.62x54R ammo fired in such a reamed chamber will exhibit a double shoulder.
Similarly, a 7.62×39 case fired in a Pakistani 44-Bore rifle will expand all around the body of the case (because of the larger diameter of the 7.92×33 chamber) and also have a double shoulder:
Note how the 7.62×39 case shows bulging around its overall length in addition to the extra shoulder.
The motivation for making rifles in this way was actually pretty simple and predictable to someone who understands Pakistani gun laws. As with many other countries, Pakistan restricts civilian ownership of firearms in “military calibers”, which include 7.62×39. The 7.92×33, however, appears to have been obsolete and obscure enough to escape official notice, and was not listed as a restricted caliber. By rechambering commonly-available AKs to this unrestricted caliber, people could own functional and legal rifles, which just happened to be able to use the “evil” 7.62×39 ammunition as well. Really, a pretty natural response to an attempt at government regulation. And in another totally predictable development, the Pakistani government proceeded to add 7.92×33 to the restricted cartridge list when this type of conversion came to official notice in 2012.
One question I’m not sure of the answer to is how magazine capacity is effected by using 7.92×33 ammunition. All sources I can find agree that standard AK magazines are used. The AFTE Journal article that is my primary source for this shows a milled AK with a 7.62×39 magazine, but I also dug up a YouTube video of a purported 44-Bore that is using a 5.45mm or 5.56mm magazine. That might actually work, since the 7.92×33 has minimal taper…but it would not work well with 7.62×39 ammunition. I will do some experiments in a week or so with various AK magazines and some 7.92×33 ammo to see what seems to work.