Thank you for your very useful response. I did have Radford's outfit as being of the pre-war militia. I have some further info on the Volunteer Militia of Missouri as it was called in the Act of 31 December 1859 which created it. All I can find are references to the following units:
1st Missouri Infantry Regiment (Cols. A. R. Easton and J. R. Pritchard, Lieut.Col. John Knapp).
2nd Missouri Infantry Regiment (Col. John S. Bowen, Lieut.Col. Alex E. Steen, Maj. James R. Shaler)
Southwest Missouri Cavalry Battalion (Lieut.Col. John S. Bowen, Maj. W. Clark Kennerly).
Jackson's Missouri Artillery (Capt. William J. Jackson)
Radford's Missouri Artillery (Capt. John Radford)
Bowen's Compiled Service Records on Fold3 contain the following:
"In the fall of 1860 (he was) appointed A.A. & I Genl with the rank of Major of the Missouri State forces consisting of one regiment and one battalion of infantry, one battery of artillery and two squadrons of cavalry sent to the Kansas Frontier under command of Brig.Genl. D. M. Frost. In December 1860 (he) was elected Lieut.Col. cmdg S. W. Battalion (Cavalry). With this battalion and Jackson’s battery (he) remained on the border during the winter preceding the war." This was a reference to the “Southwest Expedition” organized by Gov. Stewart of Missouri to counter depredations by Kansas Jayhawkers under James Montgomery. CSR continues "In March 1861 (he) was elected Colonel of the 2d Regiment Infantry organized in St. Louis. (He was) captured at Camp Jackson on May 10 1861.”
Gen. Nathaniel Lyon and Missouri in 1861 by James Peckham, American News Company, 1866, pp.132-135 (available online) lists the two regiments (including company info) of Brig.Gen. Daniel M. Frost’s brigade of Missouri Militia that was present at Camp Jackson in May 1861.
I believe that this militia was disbanded when the Missouri State Guard was organized.