A variety of other tests and other projects were conducted using MiG-3s. Leading edge slats were evaluated in 1941 although they were not fitted on production aircraft, but were used by the I-210. A six-bladed propeller was fitted on one aircraft to increase thrust at high altitude to enable the fighter to catch the high-flying Junkers Ju 86P aircraft then overflying Moscow. A new propeller hub was made that mounted six standard VISh-61 blades, but nothing more is known of the project. Four aircraft were converted to carry AFA-I cameras for evaluation and a fifth was then converted to evaluate all the improvements learned from the first four. It was approved for use after trials at the NII VVS. To improve their service ceiling two aircraft were lightened down to a weight of , but no further details are known other than one reached a height of .