Roller Delay Blowback Family from MKE

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Review : Diego Ruina
Translator: Francesco Cortellini

Among the many weapon designs from the late 70s, the HK family, based on the famous roller delay blowback system, is surely one of the most widely known.

Many reasons lay behind their fame, the main ones being the diffusion with military and police worldwide, and their longevity, as they are still in service with many forces and still in production under license by several companies, both for civilian and military/LE markets.
Among the various manufacturers that in the last few years have been offering this family of weapons is the Turkish company
MKE. This company have been manufacturing light and heavy military weapons for a long time and has recently entered the civilian market. Once incorporated into the HK holding, MKE started manufacturing several weapons under HK specs, among these are the G3, MP5, MP5K and G33, that are the subject covered in this article. At first these weapons were manufactured in their “classic” layouts with a black finish, but at IWA 2014, they were presented with a modernized look, in various barrel lengths, with desert finishings and Picatinny rails for mounting of various among devices.

The four MKE weapons that are the subject of this article
The four MKE weapons that are the subject of this article

 

The complex but sturdy retractable stock locking system . By pressing with the thumb on the release lever, held in place by a spiral spring, the internal catches engage/disengage the notches on the two bars, allowing them to slide in both ways. Save for a few minor details, the device is identical on both G3, MP5 and HK33.
The complex but sturdy retractable stock locking system . By pressing with the thumb on the release lever, held in place by a spiral spring, the internal catches engage/disengage the notches on the two bars, allowing them to slide in both ways. Save for a few minor details, the device is identical on both G3, MP5 and HK33.
The notches that, when engaged, allow the locking of the stock in the desired position.
The notches that, when engaged, allow the locking of the stock in the desired position.
The cocking handle and the indent in the cocking handle tube, that act as an hold open catch. The bolt is locked in the backward position, by manually rotating the cocking handle clockwise, until it encages the indent.
The cocking handle and the indent in the cocking handle tube, that act as an hold open catch. The bolt is locked in the backward position, by manually rotating the cocking handle clockwise, until it encages the indent.

Despite being very interesting, these weapons can be considered niche products as far as the civilian market is concerned. To be honest, we do agree that these weapons are not for everybody, and we would not suggest them as a first purchase, or weapons to buy just because you like the way they look, without knowing what are you getting your hands on to.  Stripping and maintenance require a deeper knowledge than most firearms. They are rather heavy and the moving parts are quite complex.
Customization is limited as there is only a limited range of after-market accessories, that are usually are rather expensive. These firearms were designed over half a century ago, and were based on operational needs of professional users. All this the usability by the inexperienced or untrained civilian user, that would shoot them on week end at the range.

 The front sight assembly with the bayonet lug and hand-guard retaining pin

The front sight assembly with the bayonet lug and hand-guard retaining pin
The quick release attachment for the proprietary bipod. It attaches to the rail by acting on the leaf type spring located underneath the hand-guard, and retains the ability to tilt to the sides. The attachment is fitted only to the last generation hand-guards and in the same on the G3 and HK 33
The quick release attachment for the proprietary bipod. It attaches to the rail by acting on the leaf type spring located underneath the hand-guard, and retains the ability to tilt to the sides. The attachment is fitted only to the last generation hand-guards and in the same on the G3 and HK 33
The tube that houses the non-reciprocating cocking handle ends with a "cap" that doubles as bayonet attachment
The tube that houses the non-reciprocating cocking handle ends with a “cap” that doubles as bayonet attachment
The bayonet fixed above the barrel. Bayonet and bayonet lug are the same for the G3 and HK33
The bayonet fixed above the barrel. Bayonet and bayonet lug are the same for the G3 and HK33
Another consideration about the diffusion of this weapons regards the more demanding collectors as they could be little interested in recently manufactured commercial products and more in the rarer and more valuable civilian or demilitarized HK products.
Unfortunately, also the alternatives offered by other manufacturers are quite scarce. The design is rather complex and expensive to manufacture and assemble. Save for the companies that have access to surplus components from past production runs, and those who may already have suitable manufacturing equipment, not many other companies would deem cost effective manufacturing these weapons.
The drum type rear sight. The 100 meters aperture is wider, for a faster target acquisition and wider field of view.
The drum type rear sight. The 100 meters aperture is wider, for a faster target acquisition and wider field of view.
The other openings on the drum are round holes of various diameters, placed at different heights.
The other openings on the drum are round holes of various diameters, placed at different heights.
The ZF24 optics installed
The ZF24 optics installed

Luckily there are quite a few enthusiasts, interested in using these weapons at the range not fearing to wear or damage them, without compromising the value of a rare and expensive collectable weapon, and that would be interested in the MKE products.
First, all these weapons are manufactured specifically for the civilian market; so they don’t need to comply with the regulations on demilitarized firearms. Second, the entire MKE series is manufactured to the same standards as those manufactured for the military market, using the same components, finishing and raw materials. This means a rather rough finishing, but at the same time a sturdier weapon that would withstand intense use with minimal care.

The receivers of the four weapons, it is clear that they all derive from the same basic design.
The receivers of the four weapons, it is clear that they all derive from the same basic design.
The muzzles; Treadled flash hider for the 5.56 and 7.62, quick disconnect flash hider for the MP5, nothing on the Kurtz
The muzzles; Treadled flash hider for the 5.56 and 7.62, quick disconnect flash hider for the MP5, nothing on the Kurtz
Retractable stocks of T41, T43 and T94; oily in the first one the the spring is bound to the stock assembly
Retractable stocks of T41, T43 and T94; oily in the first one the the spring is bound to the stock assembly
From top to bottom: bolt assembly of T41, T43 T94 and T94K, apart from the first one, the springs are bound to the bolt carriers.
From top to bottom: bolt assembly of T41, T43 T94 and T94K, apart from the first one, the springs are bound to the bolt carriers.

The MKE T94 and T94k manufactured for the Italian market are the only MP5 factory-chambered for the 9 x 21 mm IMI ammunition, rather than being re-chambered to 9mm Parabellum;
If, on one side, the use of a non corrosive ammunition makes the removal of the chrome lining on 2 mm at the front of the front of the chamber not a problem; on the other side the absence of the fluting at the beginning of the chamber can be a problem. This fluting, running on the entire length of the chamber, are crucial for the correct cycling of the weapon.
Their purpose is to assist extraction, avoiding the case to expand and stick to the chamber walls. The roller-delayed system is based on a delicate and exact balance of forces, that could be compromised by an excessive resistance of the spent case to extraction. In 9mm Parabellum weapons re-chambered to fire the 9×21 IMI ammunition, the last two millimetres of the chamber are not fluted, and therefore can lead to an excessive attrition, especially when firing high powered hand loads. This can lead both to excessive wear of the rollers and stoppages during firing.
Those interested in learning more about the roller system, can refer to our article about
The Roller-delayed Blowback System.

Let’s now give a closer look to these 4 MKE models

T41 calibre 7.62×51 (.308 win)

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Let’s start with the T41, G3 in HK military designation, HK 41 for the civilian market. It was the first one to be manufactured at the Obendorf workshop. Formally adopted in the late 50s, the G3(Gewer model 3) is the result of Germany’s will to manufacture its own standard issue weapon. Once the chance to manufacture the G1 rifle (FN FAL) under licence from FN vanished, Germany focussed its interests on the Spanish CETME project
MKE T43 with retractable stock and the latest model of Hensoldt FZ24
MKE T43 with retractable stock and the latest model of Hensoldt FZ24
T41 with fixed stock
T41 with fixed stock
The trigger mechanism of the T41 removed from the grip assembly. It is the same one on all 4 weapons
The trigger mechanism of the T41 removed from the grip assembly. It is the same one on all 4 weapons
The trigger mechanisms of the civilian MKE weapons
The trigger mechanisms of the civilian MKE weapons

Once the manufacturing under license was granted, the weapon was pressed into production with some improvements. As a matter of facts, that was a further improvement over a Mauser design, dating back to the end of World War 2, that was at that was at the origin of the CETME. Still today this weapon is being manufactured under license and in service worldwide. As the history of the G3 rifle is beyond the scope of this article we will not go any further.

The stripped bolt assembly
The stripped bolt assembly
The bolt head with the "wedge" shaped part that acts on the opening of the rollers
The bolt head with the “wedge” shaped part that acts on the opening of the rollers
The bolt carrier
The bolt carrier

MKE’s T41 was supplied in a hard case, with one 10 rds. magazine, a “HK style” 3 point sling made of green webbing, a cleaning kit based on the German issue one, and a manual. It was fitted with a black fixed polymer stock, polymer grip and type 2 polymer hand-guard.
According to the German regulation at that time (at least that is what we have been told) the rifle was fitted with a flat cocking handle tube cap, without hole and spring to attach the bayonet. Despite the fact that currently manufactured accessories to customise the rifle is rather scarce, on the German market it is possible to easily find several surplus parts, in different variants, at very affordable prices and in almost mint conditions.

The stock connector of the T41, in this version the recoil is attached to the the stock
The stock connector of the T41, in this version the recoil is attached to the the stock

Among these is worth mentioning the 1st pattern wooden stock and hand-guard kits, the green and black 2nd pattern polymer ones like the ones supplied with the rifle and the green and black 3rd patter polymer hand-guards with bipod attachment. Also available are the 1st pattern metal/polymer grips and the 3rd pattern all polymer grips. BEWARE! In Germany the latter are almost always supplied complete with a military trigger group. This is not compatible with the civilian version and forbidden in many countries!!! You can also get 1st and 2nd retractable stocks, foldable bipods, carrying handles bayonet attachments, slings, cleaning kits, ammo pouches and so one. The HENSOLDT ZF 24 scopes deserve tat least a few lines; these can be often found complete with all their original accessories (case, manual, cleaning kit, mount and polarized filters) in almost new conditions for a few hundred Euro.
This rifle was customised with 2nd generation retractable stock, latest version hand-guard and grip, bipod, carry handle, bayonet attachment and 2nd generation ZF-24 scope with illuminator.

T94 calibre 9×21

mke-15-1024x724The second born in the family is the HKMP5 or HK94 as the civilian version manufactured by HK was designated. It was adopted in the mid 60s under the designation MP5 or MP54. In the following years the weapon was improved and upgraded, leading to several different versions, in other calibres as well.

MKE T94 with retractable stock
MKE T94 with retractable stock
T94 with fixed stock
T94 with fixed stock
T94 attachment, the rubber buffer can be seen
T94 attachment, the rubber buffer can be seen

The MP5 is still one of the most widely known SMGs, , used and manufactured under license in many countries. Basically it sis a scaled down G3, adapted to fire the 9 x 19mm Luger ammunition.
The operating system, characteristics and appearance are very similar, most components are anly slightly modified versions, usually shortened , and some are even interchangeable. The T94 stays true to this “tradition” and appears like a scaled down copy of its bigger brother (fixed stock, old type polymer grip and hand-guard) and it was sold with the same accessories: one magazine, same case, same sling, same cleaning kit, manual with same layout. Also in this case, the offer of after-market parts is very limited compared to other weapons, even if slightly wider than that for the G3. Once again the German surplus market comes to our aid , with a fair range of parts at affordable prices. Again it is possible to source retractable stocks, latest pattern grips and hand-guards and also the Hensoldt ZF-24 with 9mm dedicated bullet drop compensation. Beware that quite often these are just standard G3 optics, roughly modified by fitting different adjustment drums. The weapon shown here features latest pattern grip, SureFire hand-guard with flashlight and 2nd pattern Hk retractable stock. Unfortunately the 3rd pattern stocks are very hard to find and very expensive.

T43 calibre 5.56mm (.223 rem)

mke-22-1024x374The third born in the family was born in the 60s with the designation of HK33. Yet one more scaled down G3, this time to accept the new 5,56 x 45 mm NATO cartridge, designed for export sales and for the Law Enforcement market.
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The G33 with extended stock
The G33 with fixedstock
The G33 with fixedstock
Stock attachment of the T41
Stock attachment of the T41

As the other weapons in this family, the HK33 has seen several modifications and improvements, and it is still manufactured and in service with many governments. The plot doesn’t change: same project, same weapon in a different size, with some adaptations, some common parts, and other parts created by joining G3 and MP5 components. In the same way MKE’s offer doesn’t change much: 2nd pattern polymer stock and grip, plain hand-guard with bipod attachment (the only type ever manufactured), plain cocking handle tube cap without bayonet attachment. Once again same packaging and accessories.
The HK33 and relevant parts were removed only recently from the German list of strictly regulated firearms, therefore the availability of dedicated accessories and after-market parts is still very limited. Until the dedicated HK33 parts will became available, the only option is to look for the compatible items originally designed for the G3 and MP5.
Meanwhile “the DIY enthusiasts” can make parts that are very hard to find on the European market , converting components originally designed for the G3 and MP5.
This is exactly what was done on this weapon. The T43 standard hand-guard, with bipod attachment, is the same used on the G3, and the rifle uses the same bayonet attachment as its 7,62 brother. AS far as the grip, we used a modified polymer 3rd pattern one, the only adaptation needed, easy to perform, being the length of the rear retaining pin.
Modifying the stock attachment is a bit harder. Looking at the original stock it is apparent that lays in between the G3 and MP5 ones. The starting point was an original G3 stock. To start with it was completely disassembled, and 5 needed modifications have been identified:

  1. Removal of the recoil spring and rod from the rear plate. We had to remove a welding point that fixed it to the plate. The hole left by this operation houses the small receptacle for the new spring; this was made out of machined steel, and welded in place. This new part is a simple concave guide, used to maintain the alignment of the recoil spring assembly, that in the T43 is connected to the bolt carrier rather than the stock.

  2. Removal of the rear sling attachment from its original position, placing it further up as correct for the HK33.

  3. Shortening and reshaping of the sheet metal attachment. On the HK33 this has only one pin hole.

  4. Shortening of the two bars of the stock. These are shorter than those of the G3, but longer than MP5 ones. Measuring and cutting take a great deal of accuracy. The sheet steel is extremely hard, so you need to proceed slowly and carefully. Once cut, the part needs to be shaped so to match exactly the new design.

  5. Once finished, the parts need to be painted or, if possible, to be phosphatized again.

The reshaped stock attachment, the sheet metal was cut, removing one of the pin holes.
The reshaped stock attachment, the sheet metal was cut, removing one of the pin holes.
The sling attachment has to be removed and held in place in the new position
The sling attachment has to be removed and held in place in the new position
And then welded
And then welded
Removal of the recoil spring and rod
Removal of the recoil spring and rod
 The sling attachment in the new position, the welding residues has been brushed off

The sling attachment in the new position, the welding residues has been brushed off
Shortened stock bars
Shortened stock bars
Reassembly
The reassembled stock needs only to be repainted or, possibly, phosphatized.
The reassembled stock needs only to be repainted or, possibly, phosphatized.

Phases 2 and 3 may seem useless, as at a first sight, the attachment on the HK33 and MP5 stocks seems identical. Despite the external appearance is identical, there is one substantial difference inside: because of the calibre is is designed for, the MP5 stock houses a simple rubber recoil buffer, while the HK33 features the same mechanical buffer used on the G3. As buffers are not interchangeable, it is necessary to start from the G3 stock, converting it. This conversion is not too difficult, and, as it is not performed on a rare historical weapon, it can be done quite light-heartedly, maybe use some little poetic licenses, using parts and finishes that better satisfy our tastes.

T94K calibre 9×21

T94K with folding stock
T94K with folding stock

After a few more years, a fourth design was developed; this time a further modification of MP5. It is only toward the mid 70s that the MP5K was designed (K stands for Kurtz: short). The weapon is a heavily shortened MP5, deprived of the retractable stock. The weapon was conceived for CQB in counter-terrorism operations, police duties, close protection personnel and special operations. Its extremely compact size made it ideal for mounted operations.

T94K with folded stock
T94K with folded stock
Most of the modification regarded the rear part of the Kurtz
Most of the modification regarded the rear part of the Kurtz

Unfortunately, the extreme compactness resulted in a rather limited effective range. This weapon has undergone several improvements and modification over the years, resulting in several variants, including a few semi-automatic ones specifically designed for the civilian market.
Completing this series, MKE designated this version T94K, and offered it with the same packaging and accessories as supplied with the other weapons.

The rear sight of the T94k (left) and the standard drum ones used on al other models
The rear sight of the T94k (left) and the standard drum ones used on al other models
The Kurtz stock folded to the side. Even if not too comfortable, it still allows to fire the weapon
The Kurtz stock folded to the side. Even if not too comfortable, it still allows to fire the weapon

Because of some German regulation, the T94K was supplied with a hand-guard that didn’t have the vertical grip, and the same polymer pistol grip as used on the other models. Some weapons were delivered with the adjustable drum type rear sight, others with a simple rear sight. Also in this case, the availability of accessories is rather scarce. The small hand-guard with vertical grip, that characterizes the original weapon is easy to find, while the most recent type of pistol grip can be obtained modifying the type used on standard MP5. As far as the stocks, (that are rather useful to allow a civilian to shoot this kind of weapon) it is possible to find both the original HK ones, that fold to the side, and adapters to fit M4 stile stocks, in both fixed and fold aside configuration. The weapon pictured here features an HK foldable stock, that looks to the side and is operated by lifting it near the joint. Even if it looks really cool, the rear plate only, with the sling attachment is of little use.

The 4 MKE.

Close up of the bolt carriers
Close up of the bolt carriers

Looking at the 4 weapons next to each other, it is clear that they are all share a great deal of common traits. Once completed the first weapon, HK has shortened the receivers, resized the magazine wells and adapted the length of the barrel and cocking handle. The bolt heads were adapted to different ammunitions and all the necessary parts were resized. The magazines have been redesigned to better fit the characteristics of the ammunitions, but the release system remains the same. The stripping procedure is the same in all 4 weapons, and it is done by removing the pins that hold the stock in place, and then the pin that holds the trigger mechanism housing/pistol grip, so to remove the grip itself.

The 4 grips in comparison, the only differences regards the rear part, where the pin housing are. Top left T41 with 2 holes, bottom left T43 with a single hole, top right T94 with a single open notch , bottom right the T94K with one hole and no rear extension.
The 4 grips in comparison, the only differences regards the rear part, where the pin housing are. Top left T41 with 2 holes, bottom left T43 with a single hole, top right T94 with a single open notch , bottom right the T94K with one hole and no rear extension.

It is now possible to remove the bolt assembly from the rear of the receiver. Separating the bolt from the bolt carrier is a little bit trickier and needs to be done following a precise sequence. Resembling these 2 components is quite difficult and it is better to avoid releasing the roller retaining spring; not a big deal if it happens, just a lot of cursing trying to put the rollers back in.

 The 3 types of magazines, the differences are quite evident
The 3 types of magazines, the differences are quite evident

All 4 weapons feature interchangeable trigger mechanisms, and can be removed, by tacking the safety lever out of the grip
Both the stock unlocking system and the trigger mechanism represent a mechanical puzzle. Those bald enough to strip them should get the relevant exploded views, and will end up wishing to have a third hand to put them back together. As in all firearms, prober lubrication is mandatory.
Despite still being effective and functional weapons, some of their characteristics are starting to show their age. They are all rather heavy and the retractable stocks are not very comfortable while aiming, especially if compared to more recent project hat provide a better cheek wield. Installation of optics and other aiming devices can be done only with the proprietary mount that, using 4 clamps and a cantilever arm, engages 4 four notches to the sides of the receiver.
These mounts are available as dedicated items for the ZF24, with interfaces for optics made by other manufacturers or with the far more practical Picatinny rail.
At the range all 4 weapons are pleasant and fun to use. With he right ammunitions they are all reliable and quite accurate. The T94 and T94K are easy to handle and control (also thanks to their weight). The two rifles are quite “nervous”, compared to other semi-automatic weapons in the same calibres, with a strong but manageable reaction when fired. Both .308 and .223 abuse the spent cases, leaving dents and marks, that cause a few problems when reloading.

The spent casing sporting the typical marks left by the fluted chamber
The spent casing sporting the typical marks left by the fluted chamber

A small note on the HK 3 points sling: after treading the sling through the rear attachment, fold it over and tread the snap hook through buckle and clip it on the small ring to the side of the front sight. The buckle has a slanted loop, that holds onto the snap hook or clips on the small hook on the hand guard, or receiver in the case of the MP5.

Installation of sling starts by treading it through the rear attachment point
Installation of sling starts by treading it through the rear attachment point
Then tread the snap hook through the buckle
Then tread the snap hook through the buckle
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The snap hook than clips onto the small ring to the side of the front sight.
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Tilting the buckle and pulling it the disengages from the snap hook and can slide freely
Tilting the buckle and pulling it the disengages from the snap hook and can slide freely
Tilting the buckle and pulling it the disengages from the snap hook and can slide freely

© Copyright 2016 Diego Ruina, All rights Reserved. Written For: Armi Militari English

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