For direct fire , the leaf was up and the slide set to 2200 yds by the lower peep. For 25 yds you used an imaginary line at 1875 yds or the open " tree" sight and aimed 12 inches low . For 37.5 yds you used the open " tree " . For 50 yds. , the top of the slide. All these used the top edge of the AT grenade as the front sight. For 75 yds. , you used the top of the slide and your front sight , leaving both eyes open to " see around " the AT grenade body.
The M1icon and 03A3s did not have a sight that could do this . The M15 was to solve this , but I have not have had good luck using it in direct , but my body build may be a factor here ( big chest , short arms ).
In indirect ( mortar type ) fire , they are all equal in thier abilities . A marked sling is good , a M15 is better , esp if you make your own range table to allow use of the 5 degree clicks rather than just the limited 30/45/60 degrees of a marked sling.
Chris