I'm really glad this thread has come this far. I've been absent a while, been busy making new products during the winter.
I finally closed my HK allocation chapter with these UMP and G36 builds.
The G36 platform is a 5.56×45mm assault rifle, designed in the early 1990s by Heckler & Koch in Germany as a replacement for the heavier 7.62mm G3 stamped steel battle rifle. The G36 family is a weapon system developped under the code name HK-50 by Heckler & Koch in Germany during the 90s after the cancellation of the G11 and G41 (first was an advanced caseless assault rifle in 4.73x33, the second was a 5.56 version of the G3, based on the HK33) and officially adopted by the Bundeswher in 1995, by 99' by Spain and more than 20 other countries in different variations.
The G36 is a selective-fire 5.56 mm assault rifle, firing from a closed rotary bolt. The G36 has a conventional layout and a modular component design. Common to all variants of the G36 family are: the receiver and buttstock assembly, bolt carrier group with bolt and the return mechanism and guide rod. The receiver contains the barrel, carry handle with integrated sights, trigger group with pistol grip, handguard and magazine socket. They come in full size "E", "K" (kurz - short) "C" (compact), and specialty configurations.
The G36 employs a free-floating barrel (the barrel does not contact the handguard). The barrel is fastened to the receiver with a special nut, which can be removed with a wrench. The barrel is produced using a cold hammer forging process and features a chrome-lined bore with 6 right-hand grooves and a 1 in 178 mm (1:7 in) rifling twist rate. The barrel assembly consists of the gas block, a collar with a bayonet lug that is also used to launch rifle grenades and a slotted flash suppressor.
The G36 uses a short-stroke piston system from which HK later developed the HK-416's impingement system. Unlike direct impingement, this system takes gas trailing the bullet to operate a piston instead of pushing directly on the bolt. The G36's bolt is operated by a cam that guides the bolt carrier by its respective cutout. Then when fully pushed forward 7 radial locking lugs fully enclose the chamber.
The G36 employs a large number of lightweight, corrosion-resistant synthetic materials in its design; the receiver housing, stock, trigger group (including the fire control selector and firing mechanism parts), magazine well, handguard and carry handle are all made of a carbon fiber-reinforced polyamide. The receiver has an integrated steel barrel trunnion (with locking recesses) and a nylon 66 steel reinforced receiver. I elected to replace the original front end and handguards with a rare Surefire G36 unit that included an integrated light, touchpad, and LED squad lights (blue) for identification.
In the box magazine is room for 30 cartridges. The magazines are molded with shock resistant plastic, and are translucent allowing the user to see the ammunition. On the sides are studs which allow for the magazines to be attached next to each other, this way the operator can reload with less hassle. For easy of availability, I converted mine to a HK416 magwell to accept STANAG magazines and allow prebans, but still have a spare G36 magwell should someone ever need it.
My rifle is a export version which has a single telescopic sight with a 1.5× magnification and an aiming reticle fixed at 300 m. I wanted to build a finished product in either K or C configuration. All rifles are adapted to use the Hensoldt NSA 80 third-generation night sight, which clamps into the G36 carry handle adapter in front of the optical sight housing and mates with the rifle's standard optical sight. The sighting bridge also functions as a carrying handle and features auxiliary open sights molded on top of the handle that consist of a forward blade and rear notch, but these can only be used with the reflex sight removed, as in the G36V. The optical sight system is produced by Hensoldt AG (a subsidiary of Carl Zeiss).
The direction I took was a complete G36K conversion with 12.5" barrel, and a separate complete modified G36C 8" front end with gas system ready to run. In K configuration, it is a pleasure to shoot, I've had some range time with the gun to ring steel at 200, 250, and 300 yards with repeatability. Very happy the way this project turned out. I should be able to bring in to the summer or pumpkin shoots later this year.
More updates soon...