Masi Bits - Pressed vs. Investment Cast

The transition from pressed lugs seems to have occurred over a period of perhaps 50 frames.  The earliest example on the Registry with investment cast lugs is #0115, while pressed examples continue to appear sporadically to at least #0157.  The easiest way to tell the difference between the two sets is to look at the seat lug.  The pressed lug frames had a plain slot in back under the binder bolt ears, while the IC lugs had a triangular cutout over a shorter slot.  On the seat tube tang, the IC lugs were plain while the pressed lugs had two small holes in a longer tang .  You can see a difference in the lower head lug as well, though it is more subtle.  On the pressed lug, the upper edge of the cutout has a pronounced curve while the IC lug's line was straighter.