Rick,
Yes, the 48 has 1/4 min clicks but only the knobs were changed and I assume that was done by a recent owner for shooting. You only have to change the knobs to do this and the staff is from the orig period. The butt plate is brass.
Is your stock a remodeled Springfield or new made?
You say yours has a heavy barrel, are there any marks on the barrel that might indicate who made the barrel?
Dan