According to an attachment that Masterpiece has provided, there are L and N frame bases. That had me wondering because the rail on the PC 686 doesn't look any different than the rail on the 629. So i tried them on the 629.. sure enough, they fit. When comparing them to the attachments above, the ones I have look to be shorter in height.
The revolver you show in your post, whilst indeed being a 629 with integral scope ring cuts, it's not the same as the first version done circa 1989.
The first version was indeed non-standard, as the usual S&W rib wasn't wide enough to take Weaver rings. Apparently S&W had Millett do a special run. By the time I got around to ordering three sets, the corporate knowledge appears to have been lost, as they sent me regular old Millett rings, minus the Millett box. All they sent were the plastic pouches with the ring bits inside. Still have one set in the spares box, unopened. Haven't gotten photos, yet! Busy week.
So two sets got modded. And have served well since the late 1990s or thereabouts.
Oddly, on the odd occasion when one of the 29s shows up locally, it usually shows no sign of ever having worn the factory rings. Last one I saw had been drilled and tapped and was wearing a frame mount! Very sad. Have yet to observe another 629 with the early ring cuts.
BTW, if there was any broaching done it could have only been on the top slots. The four side cuts were milled with a dovetail cutter. Would have to guess the top slots were milled as well, but haven't pulled mine apart recent and couldn't tell you if they were slotted with a small end mill cutter, or, more likely, a couple of side milling cutters set in a horizontal mill's arbor so they could be done simultaneously.
Will try and post new photos in a day or three.
No scope cuts here:
But it was in the handgun albums. Need to shoot it one day...
All integral scope ring cut barrels, but the PC 629 on top is wider. What fits on it is too wide to tighten on the lower two.
As noted above, the special run Milletts are narrower, so imagine the central post the width that would fall between the added milled slots. (The wings need a little narrowing , too, but I don't allow much play when the locks are tight because trying to adjust windage using the ring base screws can very easily distort the scope tube! Haven't needed to get much off optical center when dialing scopes in on these two revolvers, anyway. What was done during mounting the rings was to use a long 1" round bar in the scope's place to ensure everything lined up properly. After the rings were set on the barrel, the bar was removed and the scope put in it's place after lapping the bottom half of the rings to ensure perfect alignment and full contact.)
BTW, where in the world do you find the unbelievable revolvers you put up for auction?
