There are going to be roll mark differences between the IMI, Saco and IWI DEPs'.
I called Magnum Research the other day - thinking I had received a Mk7 with a Mk19 barrel when I originally ordered a Mk19. The service rep said that it really depends on who's manufacturing the weapon that day - that will account for what is roll marked on the weapon... WTF ?
If figured this was a BS answer, however, I've checked out several photos of the Mk19 and many of them do have different markings in different locations. The "IWI" pistols read "Desert Eagle Pistol, Mag Research, Min MN" on the left side of the frame and "IWI" / "Made in Israel" on the right hand side. The "IMI" pistols read the same info but, located on the opposite side of the frame compared to the "IWI pistol. Another pistol will have "XIX" marked above the trigger and another Mk19 won't have the "XIX" roll marked at all. Some of the older Mk19s had a skeletonized hammer, and the newer ones do not.
I have a brand new IWI (Israel Weapon Industries) Mk19 .44 Mag, and nowhere on the frame does it say "XIX". If you check out a recent production owners manual, the pic of the Mk19 doesn't have "XIX" roll marked on it either.
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It's all about different factories producing different pistols at different times. At this rate, who knows what anybody has...