Prykanbul Manufacturing Automatic Rifle, 6mm, Pattern 1914 (AR-6-14)
The AR-6-14 is a new form of weapon, one that buyers have started considering and asking for, an automatic weapon that isn't so heavy that you need a team to move it, that can be fired from the shoulder on the move and used in any situation.
The barrel is made particularly short, as short as only our fast-burning propellant allows. Its construction is light, relying instead on its heat-resistant alloy to allow sustained fire. The barrels are also made to be easily changed to permit longer duration firing. This is accomplished by means of a carry handle on the barrel, which must be rotated forwards out of a slot on the side of the receiver, then used to rotate the barrel to unlock it. The slot ensures that the barrel cannot come loose with the carry handle still in place, since it cannot rotate until the carry handle is pulled out of the slot. There is a bayonet lug on the end of the barrel capable of taking the SR-6-11 bayonet.
The action is built around a long-stroke gas piston system, with the piston assembly below the barrel. The springs, distance of travel, and gas port size are tuned to ensure a relatively low rate of fire of about 400 rounds per minute on automatic fire but a fairly powerful action so that the weapon remains very reliable even in poor conditions. It fires from a closed bolt and relies on the barrel and changing system as well as its low rate of fire to deal with heat. The charging handle on the right side does not reciprocate, and includes a dust cover section that covers its own running slot. The ejection port is sealed completely by the bolt when closed. The mainspring is captive in the buttstock, and a metal guide rod on the bolt carrier is used to push against the spring. The bolt carrier runs on two substantial rails cast into the receiver body, which allows the back plate of the receiver to be integrated into the wooden buttstock and hinged, allowing the whole action to come out of the gun in one piece (basically the FN Model D BAR). The bolt is locked by rotating similar to a regular bolt-action rifle, except it is forced to rotate via a cam in the bolt carrier rather than a soldier working the bolt directly. The whole receiver is cast and then machined to the final dimensions, saving a lot of machining time and therefore a huge portion of the cost but trading off strength, as a casting will almost never be as strong as a regular milled component. However, our metallurgical knowledge can offset this enough to allow the casting to be strong enough. The full-length rails and use of a spring long and strong enough to force the action to come to a complete stop without any impact both reduce wear and stress accumulation points.
There is a detachable bipod mounted to the bottom of the gas block, made out of a durable steel but generally as light as possible while still giving the weapon a stable firing platform. The bipod allows some left/right traverse. This allows the weapon to have a bipod mounted forwards of the center of mass, far enough forwards to give good stability and controllability, without requiring each barrel to have a bipod, or to have one detachable bipod switched between barrels. The magazines hold 30 rounds and are attached to the bottom of the rifle. They're double-stacked and double-feed, and most importantly are not disposable and instead are built to be durable and always reliable, built of tough steel.
There is a selector lever integrated into the fire control group that allows the user to toggle between automatic and semi-automatic fire. There is a separate simple safety that locks the hammer in place when it is engaged, preventing it from being dropped intentionally or accidentally. The sights are the same as on the SR-6-11. It has a separate wooden pistol grip and stock for better control when not firing from a supported position.
The combination of bottom-mounted mags and detachable barrels (detached from the right side of the weapon) mark this as a combination weapon. It must be reloaded by the gunner himself, and is easy for him to do so, but an assistant gunner can easily be added to the team allowing for more barrels and ammunition to be carried, thereby allowing for sustained fire. With one gunner this weapon acts much like an automatic rifle, with a team it can be pressed into the light machinegun role as well.
This is your first automatic weapon. It has an emphasis on light-weight design, eschewing cooling features in favor of using superior metallurgy and a low rate of fire to withstand heat. The action has a number of requirements which will call for some elegance in design: a rotating bolt on a cam is not too terribly different from your existing rotating bolt designs, and the long stroke piston is perhaps also the simplest way to make it move. However, the need to fire from a closed bolt and avoid reciprocating the handle and fire from a closed bolt adds some complexity. Detachable box magazines are another significant advancement, although you have experience designing internal double-stack magazines before which helps. The marksman rifle bipod design can be partly re-used to save precious design time, and re-using the SR-6-11 sights helps too. Detachable barrels are also a significant new feature.
Roll: 4
Difficulty: -1 (and I strongly debated calling it a -2 so don't complain that the gun isn't good enough)
Ultimately, you spent a lot of time just getting the machining on the receiver right, and the decision of where to place the gas port and the piston design also took a few iterations. When it came down to the deadline, a lot of features had to be cut. The gun essentially uses the simplest possible version of its action, lacking a safety, selector, separate charging handle, or removable barrel. Since gas in the piston is primarily released out the muzzle, the piston must be close to the muzzle for good timing of the action in this particular design. This essentially necessitates a relatively short barrel, or the piston will be extremely long adding weight and compromising rigidity.
AR-6-14: This is a gas-operated automatic rifle firing Prykanbul 6mm. It fires from a closed, rotating bolt, and feeds from 30-round double-stack magazines, which are quite fat with a slight curve. The barrel is carbine-length at 18 inches, and a gas piston underneath runs almost the full length. Cartridges are ejected from the top left, then the bolt carrier is returned by a heavy spring concealed in the stock. The force needed to rotate the bolt closed helps delay the firing process, so the gun fires about 400 rounds per minute. It includes a bipod similar to the SR/M marksman rifle and sights from the standard SR-6-11, plus a carrying handle partway up the gun. Besides this the gun is extremely barren of features. It has no safety and fires fully automatic only, with careful trigger pull single shots can be fired. The charging handle is large notch directly on the bolt carrier. The gun feeds well, and takes longer than some light machine guns to get hot, but when it does get very hot there can be issues with cartridges failing to extract (the rim bending instead) or cartridges cooking off, sometimes two or three rounds belatedly. It weighs about 22 pounds, and can be fired from standing though the recoil is significant, the gun feels to push back then pull forward in the user's hands as the long and heavy piston returns. Costs 38 credits per batch.
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Topic: Armories of Valturia: Prykanbul Manufacturing Thread (Read 7490 times)