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.
In the 1960’s the Soviets distributed their remaining stocks of captured StG.44 rifles to clients all over the Middle East. Wonder whether this increased the popularity of the 8x33mm cartridge?
The Czechoslovaks did the same and (supposedly) the Yugoslavs too in the 1960s/1970s.
Beat me to it, John. After the coup in Libya, I recall some pics floating around showing thousands of 44’s stacked up along with ammo. Blasted import laws!
Didn’t Ian post an article to that effect on FW at the time, or was it over at http://www.thefirearmblog.com? Sorry, I forget which :).
It appears that the 8×33 isn’t out of production after all… This will bite some people in the butt if someone tries making a Khyber Pass copy AK chambered for the round in question…
I’m kinda tempted, myself…Chuck form GunLab has 8×33 reamers, and I’m sure I have a spare AK around here somewhere… 😉
Good. At least you have an original AK. Khyber Pass copies are notorious for being made from not-so-great raw materials without adjusting the design. Depending on the gun smith, you might not want to buy a Khyber Pass gun. The worst of the bunch will have an extremely weak action (due to material, not design, though the action might have some tolerance issues due to the smith not having proper tools or education) likely to fail if fired with full-strength cartridges.
Some what unrelated, for awhile a local gunshop had a pile of Yugoslavian 24/47 barreled actions and I always wondered how hard it would be to convert one to 8×33 to make a funky sporter. Would it just be a magazine length issue or a chamber shape issue as well?
If you do, it would be cool to make a full length sizing die with the double shoulder, and reform .473″ headsize brass to that form.
That said, if you are loading with .311 rather than .323 diameter bullets, you might get away without having to ream or turn the 33mm necks to allow the bullet to release from cases formed from longer .473″ headsize brass.
I think normal chambering practice is to allow at least (more for military style) two to three thou of an inch diameter clearance between the neck of a loaded round and the neck of the chamber, to allow the case to release the bullet without excessive resistance.
7.92×33 caliber has a bullet of 8.2mm diameter
7.62×39 has a bullet of (interesting surprise!) 7.92mm diameter. (talking about copying 🙂
As with these accounts of STGs 44 liberated from government warehouses supposedly popping all around the Arab spring driven countries, like Libya and Syria; it is a natural question if did they tried to use 7.62×39 ammo in that rifle, as it is surely more available than the original 7.92x33mm.
We got the chamber area covered in article above, but what about the difference in barrel diameter, since here bullets aren’t meant to be “squeezed”.
There is no modification done to the barrel (other than the chamber) – they are standard production .311″ bores.
The steel core of the 7.9 mm (8.2 mm diameter) bullet is 6.13 mm in diameter. Including the steel jacket, the “hard” diameter will be close to 7.1 mm. That leaves not much lead as a cushion between the 7.62 mm lands and the bullet core when firing StG 44 ammo from an AK barrel. Probably some lead is squirted out of the back of the bullet.
Would be interesting to weigh the bullet before and after shooting.
If anyone’s interested, here’s the lowdown on the Soviet “7.62mm” bore spec.
The Czarist Army bought their tooling for rifle barrels from DWM (Mauser) in Germany in the late 1880s. This was the new-standard “7.9mm” (.311-.318″) spec as used on the M1888 “Commission” rifle. They used this as the bore spec on the M1891 Mosin-Nagant, which was known to them as the Tres Linaya, or “three-line” rifle, a “line” being an old Russian unit of measurement roughly equal to 1/10″.
When the Germans went to the “new” bore spec for the Mauser in 1898, with the .323″ “S” bullet bore, the Czar’s arsenals accordingly bought new tooling to make sure everything was consistent. But it was still called the “tres linaya”, “three-line” bore, even though as with the German rifles, the rounds for the new bore spec were unsafe to use in an “old” spec rifle due to the difference in diameter and thus, breech pressure. The main use of the new tooling, BTW, was making barrels for the Russian Putilov/Maxim water-cooled HMG. other arsenals, notably Tula, apparently kept using the old tooling, most obviously for the barrel of the M1895 Nagant “gas-seal” revolver, aka “the .32 with a higher education”.
Now, enter the Bolsheviks. Once they were in power, they decided to “modernize”, and part of that was going to the metric system. In Russia’s case, KMS was actually an improvement due to the hodgepodge of units of measure that were traditional (lines, versts, and for all I know “furlongs per fortnight”).
But they didn’t do it in any great detail, being political radicals and not engineers. Example: the Politburo, in 1930, was going to mandate that the value of “pi” was to be exactly 3. Any engineer will tell you that doesn’t work, but there were no engineers consulted.
In this half-baked “metricization” program, they noted that the “line” was 1/10″ traditionally, which was equal to 2.54mm. Therefore, the “three-line” rifle was duly “figured” to be (2.54 x 3 =) 7.62mm, without anyone ever actually checking the bore spec or even looking it up.
This is why Russian or similar “7.62mm” rifles can have bores ranging from .311″ to as great as .323″. It depends on where they were made, and what vintage the tooling they were made on was “descended” from. Generally speaking, it all conforms to one of the two DWM bore specs, original or “S”, with the latter being more common in the former WARPAC countries in Europe. Norinco in the PRC also generally used the .323″ on their AK and SKS clones.
Outside of those areas, in Egypt, Indonesia, etc.- who knows?
Best advice- slug the bore and mike it. And even then, proceed with caution in choosing bullets for handloading. It’s better to be safe than bulged or blown up.
cheers
eon
Sorry, eon, the German part of your story is what many people believe, but it is not quite correct.
The bore dimensions for the German 7.9 mm were not changed when the S-bullet was introduced. The S bullet has a larger diameter than it 88 predecessor. But only the neck part of the chamber was changed accordingly. The bore itself remained unchanged. (Very similar to what the French did for balle D.) Bore dimensions for Gewehr 88 as well as Gewehr 98 etc. were 7.9 mm +0.04 mm having 4 grooves 0.15 mm deep (which adds up to 8.2 mm).
The smaller 8 mm bores (8x57I) were strictly an invention of the commercial gun trade in Germany, based on wrong beliefs what would be good for accuracy. The 8x57I has nothing to do whatsoever with the military 7.9 mm (today called 8x57IS).
I am used to encounter disbelief on this matter, but -while in reality there are some additional quirks- the above are the well documented basic facts.
OK, I stand corrected. But the Czar’s arsenals did use German tooling. Which could mean that the variances in Russian/Soviet bores may simply be due to sloppy specs or poor quality control.
I formerly owned a Mosin-Nagant M91/38 that miked .322″ groove, .317″ land, and a Brno 1943 Kar98K that went .323″ and .318″ respectively, all using the same inside mike. A pair of MAK-90s miked with the same instrument showed .322″ and .318″ land/groove. I don’t know what the bore spec on Ruger Mini-30s is, but I do know that friends who handload for them with .308″ bullets aren’t happy with the results, accuracy-wise.
BTW, a Nagant revolver made in 1945 I had at that time checked in at .315″ land and .317″ groove. So there was apparently some variance in actual bore diameters, even if there was supposed to be just one spec.
I’ve also seen P.08s with barrels marked 8.9, etc., indicating that the bore was below or sometimes above the “ideal” spec but within the acceptable limits.
My best guess is that the variances were fairly wide, and if the barrel was within them, the Russian Army and German Army didn’t get their backs up about it. Especially not when everyone was “aiming for effect”, as the old saying goes.
cheers
eon
Hi Eon,
Early Ruger mini 30s had .300/.308 bores, and were throated to allow either .308 or .311 diameter bullets to be used.
With increasing popularity of 7.62x39mm in the united state, and the appearance of more .311 bullets in the appropriate weight range for reloading, that may have changed – semi auto centrefire rifles were banned here and (the legally held ones) confiscated back in 1988, so I haven’t kept current on such details.
Keith;
Thanks. As the old saying goes, A-ha! So that’s it.
Myself, I stick to factory ammunition. That way, if anything goes wrong, I know it’s not my fault as long as I read and adhere to the instructions.
“Half of being smart is knowing what you’re dumb at”, as my mother used to say.
😉
cheers
eon
About caliber measurement:
http://en.wikipedia.org/wiki/Caliber
“In a rifled barrel, the distance is measured between opposing lands or grooves; groove measurements are common in cartridge designations originating in the United States, while land measurements are more common elsewhere.”
Therefore for example Russian 3-line Nagant 1895 is .32 weapon in American measurement
A couple of of years ago I was involved with importing a couple of firearms from Pakistain.
At the time I was told about the 7.92×33 AK’s. I thought this cant be true, and I didn’t want any talk of automatic weapons interfearing with the deal. I for just said no and turned my head which in Pakistain means “F-No”. Now I wish I hadn’t been so rude.
PS
don’t think for a second that Pakistanies don’t take care of thier fierarms. The gun culture there is strong. Ownership is a status symbole. Dean
i have seen pix of a group of 15 MP44 in pakistanese gun shop.
local production ? old surplus ?
https://picasaweb.google.com/102165525929900773620/DemillingOfMP44For3rdTransaction
https://picasaweb.google.com/102165525929900773620/ExportGunsToEurope#5398271082593656290
https://picasaweb.google.com/102165525929900773620/Mp44ChooseOpeningStyle
https://picasaweb.google.com/102165525929900773620
They look like original German-made guns to me.
On the topic of .303 to 7.62 x 54 conversions, someone suggested this a while back for Lee-Enfields. I’m not sure if my favorite rifle would handle this – isn’t the Russian round quite a bit more powerful?
On oddball STG-44 variants – I’ve seen pictures of both French and Italian ’44 clones from the postwar period chambered for .30 Carbine. Apparently because of the widespread distribution of M1s and M2s to European allies and re-armed former enemies, neither version ever went beyond the prototype stage.
SAAMI lists max pressure for the 0.303in as 49,000, and 7.62 x 54R as 50,500. This is for factory rounds and safe handloads, and assumes a margin of safety of 12% over listed pressure to allow for older weapons whose metallurgy is open to question. Original No.1 MK I SMLEs or early production M1891 Mosins, for instance.
While you might get away with this in a Rifle No. 4 in good condition (say, a 1950s production from Long Branch or Fazakerly, or a 1960s Indian production), I wouldn’t want to try it. All things being equal, I’d either invest in some Remington .303 “Light Magnum” ammunition, or try to acquire an Enfield Enforcer in 7.62 NATO. Even factory loads generally outperform the .303 or 7.62 R in that caliber.
cheers
eon
Very interesting article. I am particularly interested in the .303 to 7.62x54r conversion idea.
.303 to 7.62x54R conversion:
http://jpfo.org/filegen-n-z/smle.htm
states: “.303 Chamber Pressures; 45,000-48,000 PSI “54R” Chamber Pressures; 45,000 PSI”
My note: There are many variants of 7.62x54R Mosin ammo, some were developed for machine gun for example ShKAS ammo (headstamp: Ш) is not interchangeable with standard Mosin rifle.
The comparison of chamber pressures also needs to take account of the larger head size of the 7.62x54R.
I haven’t run the figures to see whether /54R gives more backthrust than a 7.62X51, which is known to be safe in a No4 action.
I’ve just checked the case dimensions on wikipedia (not the most reliable) If they are correct, then the rim thickness (headspace) is the same for .303 and 7.62×54 R, though I wouldn’t fancy my chances firing a .460 head diameter .303 case in a x54 chamber with head diameter of .487″.
interestingly, the .303 case head is slightly larger than the 7.62x39mm head, so assuming the same elasticity of brass and the same chamber pressures, putting a 7.62x51mm chamber in an otherwise unaltered .303 No4 might (very big uncertainty) allow both .303 and .308 to be used.
Certainly there is the problem of extractor and ejector, allong with .308 versus .311 bullets
rim thickness (data from http://www.municion.org/)
7.62x54R – 1,35mm (http://www.municion.org/762x54r/762x54r.htm)
.303 British – 1,60mm (http://www.municion.org/303/303.htm)
I’ll gladly take those figures over wikipedia ones any day of the week.
Yugoslavia actually considered making a copy of AK when 1st one was acquired in 1956. But then whole 7.62x39mm and SKS production line were acquired for cheap in late ’50s so plan was canceled.
Dear Kieth,
When the No 4 was converted to 7.62mm Nato a new bolt head was used of steel 8620. When the Indians converted (and made new) they also used a new bolthead in this steel.However during WW1 the Turks captured many 303″ No 1s at Kut and converted them to 7.92mm X 57mm. The Lee Enfield actions will not crack under extra pressure (unlike the Mauser) they just stretch and eventually jam.
Thanks John,
out of interest, have you any info on the depth which those bolt heads were case hardened to?
John
What reference did you get the steel spec from?
most which I’ve seen have been singularly illiterate in terms of materials.
One ref (can’t remember which) described how the Indians had upgraded to “EN steels” for the 7.62mm SMLE, without stating which EN steels.
EN standing for “Emergency (or “Engineering”)Number”
a system of labeling steels which Britain adopted prior to WWii, so that an actual composition could be given for the steel spec, rather than some obscure proprietary name for an otherwise commonly available steel.
Of course, unlike the SAE system for labeling steels, EN carries no indication of the composition of the steel, so EN1 is a mild steel such as SAE 1020, EN1a is free cutting sulphurized or leaded mild steel, EN8 is a plain carbon high tensile steel (SAE1040) and EN19 is a chrome moly (SAE4140)
I happen to have an Ak-44 at home gathering dust. It has been in the family for sometime now.It is usually called ‘Chuta’ali’ here; an Urdu word for 44. If you people have any specific questions about it I will be very happy to answer them as best as I can.
Hi Adi – I would be interested in hearing what type of magazines you use in the rifle. How many rounds will fit and feed reliably in a 7.62 magazine, vs a 5.45 or 5.56 magazine?
It uses standard AK steel mags. I have not seen any other being tried in it.
Full magazine takes 28 rounds but I don’t put more than 20 in it.
Feed issues happen usually when the cartridge dips because of excessive space between the tip of the bullet and the magazine wall. Other than that, feeding is not that big an issue.
It has a milled receiver with no identifiable markings except the arrow which I guess the gunsmith put on it as he saw them on Russian AKs.
I only came to know about the presence of this gun in the family about two years ago.The gun had been neglected for sometime and developed all kinds of problems due to rust. It had a free floating firing pin which was stuck forward. I wasn’t that familiar with firearms at that time. I went out, cocked it and it fired! Imagine the dumb look you have when you have no idea what had just happened. Luckily the selector was on single shot or the whole magazine would have gone out.
I spent a couple of WD-40 cans on it, watched the AGI’s Ak armourers course to understand what had really happened, cleaned it all up and put it back together. It is in good working condition now.
I have emailed you some pics of the magazine and head-stamps on bullets. I hope they help.
Thanks, Adi – I appreciate the info. I didn’t get an email from you, though – can you try sending it again?
I sent them again. I hope you got them this time.
Yep, just came in. Thanks!
Dear Kieth
The No4 bolt head was probably hardened at 0.010/0.015″,as was the 0.303 bolt head. I think that EN stands for engineering number and is now superceeded by European specs.The conversation of No4`s from 0.303″ to 7.62mm was tried by target gunsmiths in the 1950`s as follows.No4`s were selected with low range bore diameters and re-chambered for 7,62mm. The extractor will work in 7.62mm and the mag was not altered as it was planned for match shooting and was not used. The results were that the accuracy was not good enough although it was alright for cadets or hunting.
On the subject of 7.62/7.92 AK rifles the AK mag will only take about 15 rounds of Kurz but will not feed as the rounds are pointing down too much,only the last 5 work satisfactorily.Of course the AK mag could be changed but that could result in a mix-up later. Anyway is anyone saying that there is a shortage of MP44`s on the world market!!