Firecracker

Unveiled by Nobel Industries in 3063, the much-maligned Firecracker was the company's first and only venture into the BattleMech market. Nobel Industries had long been a major producer of arms and explosives for the Lyran Commonwealth, but in the wake of the Clan Invasion, the company's aging CEO and Chairman Duke Redmond Nobel became increasingly obsessed with a delusional belief that the Clans' technological superiority would lead to a dramatic reprioritization of resources towards the construction of vast fleets of WarShips. This would in turn lead to a dramatic reduction in the prevalence and scope of BattleMechs and armored vehicles on the battlefield, and instead when ground engagements did occur they would (for some reason known only to the Duke) be reduced back to massed infantry formations slamming into heavily fortified static objectives. With his obsession fueled by a rapid deterioration of his grip on reality as he rapidly approached the end of his life, the Duke was convinced that his company's survival depended on adapting to this imagined future. The rest of the company's board of directors managed to shut down Duke Nobel's plans to shift the entire company towards WarShip production, but they were still forced to allow him to dedicate resources towards some form of smaller-scale project.
That project, ironically enough, would materialize in the form of a BattleMech. What Nobel envisioned was essentially a walking machine-gun turret, designed to carry as much ammunition as humanly possible in order to allow the mech to sustain fire for absurdly long periods of time without support. For protection, four tons of Blastopper 2000 standard armor was considered adequate to allow the mech to shrug off most man-portable munitions, while a Pitban 100 XL engine with an XL gyro would allow for the bare minimum of mobility while providing enough weight savings to allow for every last bit of available space on the mech to be filled with ammunition. Ten single heat sinks provided cooling, with a full three dedicated towards cooling off each of the 'Mech's two Nobel PeaceMaker machine guns during long, uninterrupted periods of sustained fire. And, of course, feeding those machine guns was a whopping 7,000 rounds of ammunition weighing in at 35 tons, accounting for over half of the 'Mech's total loaded weight and allowing for just under eight minutes of sustained fire at 900 rounds per minute without resupply. Completely convinced that his creation, dubbed the Firecracker, would be a runaway success, Nobel ordered that an initial stock of 7,000 units be produced before it was revealed to the public and put on sale, one for each round of ammunition it was capable of carrying.
The 'Mech immediately became a laughing stock, with ordnance board officials and mechjocks alike joking that the name, intended to evoke the sound of its machine guns firing ceaselessly, instead signified what would happen when enemy fire breached the inadequate armor and touched off the ammunition. The 'Mech was a resounding failure, with Nobel Industries failing to move more than 50 units by the end of its first year on the market, with most being sold as police units to impoverished Periphery states. Duke Nobel took his creation's failure with outright confusion and animosity, ultimately leading to him being institutionalized after he bit the face of a Lyran acquisitions officer who interrupted a sales pitch to openly ridicule the design. By the end of its second year on the market, Nobel Industries cut their losses and sold the remaining 6,900 units of stock off to be stripped down for materials.
The design would, however, see limited new life during the Jihad. During their push into the Lyran Alliance in 3068 with Operation STEEL HAMMER, the Word of Blake captured several of the scrapyards to which the 'Mechs had been sold. Once Devlin Stone's Coalition forces began pushing into the Word of Blake Protectorate in 3077, suicidally desperate Word of Blake militia discovered that the tremendous ammo explosions produced when the 'Mechs were destroyed had a tendency to take anything in the immediate area with them. This resulted in the 'Mech being deployed in limited quantities by Blakist forces as suicide units in urban environments, where limited sightlines would often result in Coalition MechWarriors being forced to engage Firecrackers at close range, where their own 'Mechs would be destroyed or otherwise heavily damaged in the resulting explosions. Blakist forces would also occasionally weld their fellows into the cockpits of Firecrackers as punishment for cowardice, with the Coalition's hunger for Blakist blood being such that any manned units in Word of Blake colors were almost guaranteed to be engaged without warning or chance to surrender. In such cases, the entombed Blakist's only hope of survival was the nigh-impossible task of expending all of the 'Mech's ammunition before being destroyed, as only then would it be possible for the 'Mech to be destroyed without causing a massive explosion that would inevitably consume its pilot.
Despite this brief spike in usage, the end of the Jihad would see the Firecracker fade into obscurity, all but forgotten except as a curious footnote in the history of the BattleMech.
Technical Readout, record sheets, and MegaMek files available here.