Transient execution attacks pose information leakage risks in current systems. Disabling speculative execution, though mitigating the issue, results in significant performance loss. Accurate identification of vulnerable gadgets is essential for balancing security and performance. However, uncovering all covert channels is challenging due to complex microarchitectural analysis. This paper introduces SpecScope, a framework for automating the detection of Spectre gadgets in code using a black-box microarchitecture approach. SpecScope focuses on contention between transient and non-transient instructions to precisely identify and reduce false-positive Spectre gadgets, minimizing mitigation overhead. Tested on public libraries, SpecScope outperforms existing methods, reducing False-Positive rates by 8.9% and increasing True-Positive rates by 10.4%.