Many Marylanders served in prewar Maryland Militias such as the famous 53rd Maryland. They would have most likely utilized the US Army manual of the time (Hardee's since it was implemented in 1853).  When 1st Maryland Infantry was formed in 1861, it is logical they utilized the drill they were accustomed to.  With the fact that the 1st Maryland Infantry was armed with mostly the 2 band Mississippi Rifles, it would be very logical and ideal they used Hardee's esp since the 1853 version was written specifically for the short 2 band rifle (Hardee's was later revised in 1862 for the 3 band rifle). When the 1st Maryland was disbanded, the officers and men reformed the nucleus of the new 2nd Maryland Infantry in 1862.  Again, it is logical to presume they carried over the drill they were familiar with to implement in the new unit. Screen shot above is an excerpt from Company D's very own Lt. McCullough's diary.  The excerpt not only details yet again Marylander's proficiency with drill but also says point blank they used Hardee's drill.  As far as I'm concerned this is case closed of drill manuals used by 2nd Marylanders unless evidence produces the fact they changed later in the war (this is very doubtful though).

 Co “D” 2nd MD INF C.S.A. 2014