USPSA Limited Optics rules + cross-platform build guide for 2026. Compare Staccato XC, Bul Armory SAS II, CZ Shadow 2 OR, and Tanfoglio Stock 3 OR head-to-head on weight, cost, and reload speed. Legal magwells, 140mm base pads, slide-mounted red dots — what's allowed, what's banned, and the cheapest competitive turnkey build under AUD $2,600.