In a recent study, the 30-question Force Concept Inventory (FCI) was theoretically split into two 14-question "half-length" tests (HFCIs) covering the same set of concepts and producing mean scores that can be equated to those of the original FCI. The HFCIs require less administration time and reduce test-retest issues when different versions are used in pre-post testing. This study experimentally evaluates the practical validity and measurement uncertainty of the HFCIs with three different college student populations. Measured mean scores on each HFCI were within ~3% of each other at every university. Measured mean score differences between the HFCI and FCI were also within ~3%. These differences are less than the value of a single question on the 30-question FCI and are not statistically significant. The overall results suggest that, in conditions similar to this study, the HFCIs can be used as alternatives to the full-length FCI when total scores or score gains are the measurement goals.