Report Springfield Hellion: Bullpup 5.56 in Semi Automatic Rifles Posted March 3 · Edited March 3 by Astro14 Pricey, but interesting. I don't think the Croatian origin is a negative. My XD-M is a well built, good performer. I like how compact the bullpup is, and wonder how this compares with the Tavor. I will say that I like the ambidextrous ejection option as well as the adjustable gas system.