Nice.
If those are the later production TSW's, made '06-'07 or later, they have all the latest revisions and machining improvements.
There was a 4566/63TSW barrel revision back about '06, which I only noticed by accident when comparing barrels of 2 new production 4566TSW's we'd received. The barrel lug at the rear of the barrel looked different on each of them, so I called the factory and asked about it. I was connected to one of the engineers by a tech guy I knew (as an armorer who had called about questions now and again). The rear barrel lug (ring) that used to fully encompass the barrel ahead of the chamber was changed, meaning the it was eliminated on the bottom of the barrel. I was told that ongoing R&D had caused them to determine it was no longer required to be machined on the bottom of the barrel, and served no purpose. (The barrel's feedramp and chamber mouth, meaning the roll-over notch at the top of the ramp, also looked a little smoother and cleaner on the revised barrel.)
This was about the same time I noticed they'd started removing (or "pre-breaking", as it was described) a thin section of steel on the left side of the firing pin channel, adjacent to the ejector depressor plunger channel (on the rear), connecting those two machined channels at the rear. I was told that newer machining methods allowed them to remove that small section of steel, which had normally been subjected to developing a non-critical "crack", anyway. (You'd never be able to see it unless you removed the manual safety assembly and knew what to look for, anyway.
)
Kind of like how the thin section of steel underneath the extractor, inside the R/side of the slide's channel next to the pickup rail, used to develop a curved crack, or one small side of the disconnector notch used to have that thin section of steel break and fall out. I was told that newer production methods allow them to remove those thin spots of steel where stress risers often developed and caused those non-essential small bits of steel to break off and fall away under repeated recoil.
Anyway, you've probably got your hands on the last state-of-the-art 4566TSW's to come off the line. Congrats.
I had a chance to buy one of our late-production 4566TSW's when they were phased out, as I'd briefly carried one as an issued weapon back about '07, but passed on it in favor of buying a 3913TSW. I'd hand-selected that particular 3913TSW when it was unissued and still NIB, and carried it for only a brief while before the TSW's were all replaced with M&P's. Our late production TSW's all had the riveted rails, because the guy who had ordered our new stock had declined the offer of having the 4006/4566TSW's produced with the machined integral rails (at no extra cost).
They were also ordered without the Melonite treatment.
