In the late 1980s, the Spanish gunmaker Star decided to join the new hot trend of 10mm semiauto pistols. The cartridge was getting a lot of press, and Star saw this as an opportunity too ride the wave and also the get a pistol on the market that would attract IPSC competitors. Unlike some companies adapting existing .45ACP designs to 10mm, Star decided to start from scratch to build a pistol that was massive and durable; able to handle the power of the cartridge without any worries.

Star engineer Eduardo Zamacola (who had previously designed the M38/30/31 series for Star) had the first prototypes ready in 1990, in both 10mm Auto and .45 ACP. The design took cues from the Petter designs of France and SIG, with full-length internal slide rails and a removable modular fire control system. It offer 12 round capacity in .45 and 14 rounds in 10mm.

The pistol was quite massive and heavy (1.4kg / 3.1 lb), and failed to sell well from the start. The 10mm craze and flared out rather quickly - it remains a niche cartridge to this day, despite periodic releases of new 10mm pistols (the SIG 320 in 10mm being the most recent). What really killed the Megastar, though, was the 1994 Assault Weapons Ban in the US. This prohibited new magazines holding more than 10 rounds, and the whole point of the bulk of the Megastar was to allow larger double-stack magazines. With those no longer available, there was really not much reason to get a Megastar instead of something like a 1911. In total, just 978 were made in 10mm and 5,424 in .45ACP, with production ending in 1995.