I don't know about this TSW thing, but I've found all 17 of my 3rd generation pistols, as well as my one, only and lonely little 2nd generation, shoot about like the 5903 below (when I do my part), and none of them have TSW anywhere in the model number . . . Heck, even the Econo Model 915 does pretty well without TSW on it.

That said, if I could pick up a 99% 4513TSW pre-rail, I would jump on it. Not because it might tighten my groups by a 1/8" or anything, but because it was only made for a year and is hard to come by.

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1st Signal Brigade, RVN '70