Hammer heights by frame size (measured vertically from bottom of foot to highest point of the hammer top, not the spur) pre war are the same:
J & I frame, 1 5/8” in height
K frame, 1 ¾” (inc. 1st short throw “hi speed action hammers”)
L frame, 1 7/8”
N frame, 2”
Note: EARLY TRIPLE LOCK HAMMERS DO NOT INTERCHANGE WITH LATER HAMMERS. Also TL and 1917 actions actually have a shorter action than later pre war N frames. In the Neal and Jinks S&W 1852 – 1945, page 206, section on the .44 HE 2nd Model, it states "the…hammer fly was changed to increase double action throw…".
TL early Convex foot and trigger, both with chaffing bearings:
Photo by LLOYD17
Later TL with Concave foot on this 455 TL (still has chaffing bearings) and will interchange with later pre war hammers:
Photo by LLOYD17
TRIGGERS may be the same size for K, L & N frames but the pre war triggers won't interchange based on the vintage due to the style of the hammer block safeties.
Trigger for 1st style side plate hammer block safety:
Photo credit: NH Old School
Trigger for 2nd style side plate hammer block safety (same as all post war triggers with sliding bar hammer block safety):
Photo credit: NH Old School
Side view of triggers above in the same order:
Photo credit: gordonrick
Type 1 left, Type 2 right - side plate hammer block safeties:
Photo credit: gordonrick
