Joshua Mk5

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Joshua Mk5

Post by el_jefe on Thu Sep 08, 2016 10:18 pm

http://www.gunsweek.com/en/rifles/articles/joshua-mk5-arak-hybrid-rifle


A new kid in the block

Designer Ryan Croft named Joshua rifle system after the victorious Hebrew general referenced in the Old Testament. He envisioned the weapon as the tool for the righteous, a rifle that would perform well and could be maintained with minimal facilities. The original was simply a 5.56mm AK with a STANAG mag well. Several subsequent designs were developed but not produced, until MK5 came out. It was intended to make a civilian DMR to offer precision shooting out to the limits of 5.56 cartridge envelope.
The Joshua MK5 is chambered for the 5.56x45mm/.223 Remington caliber, and feeds through STANAG magazines



Part AK, part AR, all MSR

The heart of MK5 is the AK bolt, carrier and trigger group. The 2-lug rotating bolt and long stroke piston follow the reliable, combat proven AK operating system. Unlike the thin stamped AKM receiver that flexes substantially during the firing cycle, MK5 receiver is a rigid milled 6061 aircraft aluminum receiver serial-numbered “core” insert inside a larger milled frame. It provides a more consistent support for the barrel and for the trigger components. A steel mag well ramp insert and AR-style barrel feed ramp ensure reliability with STANAG magazines.


The gas system is more similar to FAL, with an adjustable regulator. Gas flow can be increased to make a dirty rifle run, or reduced to minimize recoil under range conditions, or turned off entirely for straight pull action suppressed. Gas system parts are made from 316 stainless and 4140 hardened and nitride treated steel. The gas system is locked into place using an interlocking design that does not drill or interference pin the barrel, so the point of impact shift upon heating up is minimized. Direct 90 degree viewable access to the gas port allows for efficient cleaning.

The sighting is based upon a monolithic rail running the full length of the receiver and the handguard. Enough Picatinny slots are provided to use a scope in tandem with a night vision or a thermal device, or to co-witness a red dot and iron sights. The rail comes off with the sights attached when the rifle is cleaned, and returns them to zero thanks to three alignment points. While AR-height optics and iron sights can be used, the stock is offset slightly further down from the Picatinny top, and so medium scope rings would bring optics closer to the bore line. A trough in the top rail is provided as a gutter sight, in case the optic fails and no backup sights are available. Enthusiasts of iron sights will appreciate the substantial sight radius provided by the monolithic rail.


The 16.5” tapered heavy barrel is CNC turned using a proprietary “infinite noise” method to reduce the effects of subharmonic generated vibrations across the skin of the barrel, thereby reducing heat loading, barrel oscillation amplitude and duration. I don't have the engineering background to evaluate the method, but the result is a semi-auto rifle achieving 0.5MOA with 55 grain PMC Bronze ammunition! The taper helps to even the balance while retaining substantial heat sinking capacity. The specially calculated forend internal volume further helps cooling by introducing turbulent air movement around the barrel. The aluminum forend was meant to draw heat away from the chamber area and radiate it outward, improving sustained fire performance without cook-offs.

Accuracy and intended role

In its 5.56mm iteration, Joshua 5 fills the role similar to the Israeli Galil ARM support weapon, originally a light machine gun that has been relegated to designated marksman use with the reserve option of high volume of fire. A slightly shorter barrel is used because a civilian defender may have to operate alone, and so must be more mobile. Making extensive use of lighter alloys, MK5 weighs only 8.4lbs compared to ARM's 9.6lbs.

The high-precision manufacturing with generous clearances in the action combine for AK-like reliability without internal battering associated with inconsistent mating of metal surfaces. The two-lug bolt is precision-mated to the receiver to ensure a very high degree of contact with the locking surfaces. All parts are either hard anodized or given nitride treatment. While most MK5s were shipped with Magpul MOE or PRS stocks, several customers specified the orthodox AKMS folding stock – Joshua 5 had an optional receiver opening to install it.


In use, MK5 is extremely comfortable. Supplied with the Army-standard A2 flash hider, it has no need of a muzzle brake. Recoil is very light, and muzzle rise is negligible as well. Fired from a bipod, it moves so little that the shooter can spot hits through the scope even at close range. Unusually for 1:7 barrel twist, it shoots very well with lighter bullets, a helpful feature for a survivalist weapon that may have to run on whatever fodder is available.

I got about 1.2MOA with Federal Gold Match 69gr, 1.6MOA with PPU 62gr FMJ-BT and, surprisingly, 4.4MOA with Allegiance 100gr subsonic. The round nose powdered tungsten frangible load seldom functions or stabilizes at all in general purpose semi-autos.
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el_jefe

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Re: Joshua Mk5

Post by el_jefe on Mon Sep 12, 2016 2:20 am

According to locals, these guys have a less than stellar business reputation.
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