Decimal International SR-12 Anti-Material Rifle : r/worldbuilding
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MX-G6 AMR (Anti-Material Rifle) by GunnerGoat on DeviantArt
MICOR Defense Leader 50 Ultra-Compact, Lightweight Bullpup Semi-Auto .50 BMG (12.7x99mm NATO) Sniper/Anti-Materiel Rifle and PNW Arms Weapons Science .50BMG Ammo at NDIA Infantry Small Arms Systems Symposium 2011: Potential Long-Range Lethality
GM6 Lynx: The Hungarian Long-Recoil .50-Caliber Bullpup - YouTube
Steyr Bullpup Anti-Materiel Rifle by mongoose01 on DeviantArt
St. George Arms Leader 50 A1 Ultra-Lightweight, Compact Bullpup Semi-Auto .50 BMG Multi-Caliber Anti-Materiel/Sniper Rifle is Less than 40 Inches Long and Weighs Less than 18 Pounds!: Ultimate Shoot-'n-Scoot .50 BMG Mega-Blaster