ZA-4 "Shard Rifle"

Little is known about this weapon used by Hive Marauders and on rare occasions other Hive entities. Upon being discovered by the Dragon Alliance, the weapon was codified the "Shard Rifle" due to it's ammunition being shards of glass that are black like obsidian but wildly different in it's molecular makeup than standard glass. Designated the ZA-4, the Z denotes that the weapon is from an unknown origin while the 4 is the 4th armament captured and catalogued from the Hive's aresenal. The shards fired by this weapon act more like tempered glass in that when they hit solid enough objects they completely shatter, allowing the glass to cause secondary injury to the limbs, neck, head and other nearby troops. That action alone is not very impressive as it acts just like any other bullet that breaks on contact with a hard surface but with far inferior armor piercing capabilities, what the rifle itself does to this glass is what makes it a deadly threat on the field.
The Shard Rifle operates by infusing the glass with a powerful electromagnetic binding field which essentially keeps the shard held together when it hits it's target. Upon impact the electromagnetic field rapidly dissipates into the target and surrounding air which will then allow the glass shard to break up. This gives it much similar properties to a bullet and the field allows the glass shard to stay together giving it armor penetrating capability on par with most military rounds.
Another discovered effect of this rifle is what actually gives it it's infamous reputation. There is something infused in the crystals themselves that causes a catastrophic molecular reaction with the calcium in bones, which means that enough hits from a Shard rifle will actually cause a fatal cascade in a skeleton which then will detonate, ripping apart the target as well as turning them into a biological grenade, severely injuring anything within 5 meters of the victim. It is possible that the bone shards from the victim will carry some of the catalyst with them so there is a small chance additional targets will explode as well, causing a chain reaction. It is unknown if this effect is inherent to the crystals themselves of if it's another effect infused by the rifle in the process of firing.
The firing process of the Shard Rifle is a mystery to most of the scientists in the Dragon Protectorate. What's known about it is that, similar to a normal rifle, a chunk of crystal that's vaguely shaped like a magazine is inserted in a slot on the bottom of the rifle where it acts like any magazine would. When the weapon is "empty", the crystal is removed and upon inspection the middle of the crystal will be carved out leaving just an outer husk of a crystal, just like an empty magazine. This phenomenon is not understood and is the subject of intense study.
The weapon has a trigger and when pulled the Rifle activates, infusing the absorbed crystal from the "magazine" with the electromagnetic binding field to keep it from breaking apart. The weapon also infuses the barrel with a rotating charge which will then propel the projectile out of the weapon at speeds of up to and exceeding 1300 m/s. The weapon itself acts more like a pseudo rail gun. Some even question it's designation of being a "rifle" because the barrel of the weapon is not rifled, it's smooth prompting some to refer to it as a smoothbore cannon instead. Either way, the weapon is incredibly accurate.
The AcDragonians began an exhaustive study on this weapon to attempt to not only reverse engineer it but to figure out how it's technology can be exploited in their own weapons. What they discovered so far is the weapon doesn't have a loading mechanism like traditional rifles. The weapon seems to "absorb" the ammunition from the crystal magazine. Upon further probing, it seems that the weapon has the ability to be charged further by holding the trigger and upon release will fire out a crystal slug that uses more of the ammunition. Tapping the trigger as fast as possible, the AcDragonians were able to get about 20 shots before a reload was needed. While holding the trigger as long as possible before the gun automatically released the slug, they got about 4. Curiously, the slugs released when fully charge are not physically bigger, however they are far more dense, making them much better at armor penetration, anti-vehicle capability, pure knockdown power and a much more lethal bone detonation. The weapon almost seems like it was created as a general purpose rifle that gives the user all the tools they need to adapt to any situation. The only thing missing is some kind of suppressive mode however the AcDragonians aren't sure if there's some kind of function that need switched to achieve that. The lack of a magnified sight seem to imply the weapon isn't meant to be used as a DMR.
The AcDragonians have a company of soldiers who exclusively use these rifles. Not only to put them through extensive field tests, but to also more effectively hunt the marauders with their own weapons.