Okay, it's a new model 66 - sort of like the New Vaquero. S&W has made some changes and "improvements" to the original to meet certain demands.
1. Yes, it has the lock (aka Hillary Hole). Do what I do, unlock it and ignore it.
2. "Barrel serration" refers to the longitudinal grooves on the top of the barrel that reduce glare when using the sights.
3. New guns will come with MIM parts. Deal with it.
4. New guns will comes with frame-mounted firing pins. Just as reliable and less prone to breakage than the hammer mounted ones.
5. Ball-detent lock-up is a feature to ensure a solidly locked swing arm.
6. Two piece barrel (see discussion below)
First and foremost, from what I can see of the gun in the S&W video, it is most likely a redesigned K-Frame. This means its dimensions vary from the older K-Frame line somewhat. There are several reasons for this, including to beef up the gun for .357 use.
I purchased a 2.5" Model 66
-7 in 2004. It has all of the above features except the serrations and was one of the last Model 66's produced before they discontinued the model. Here's a photo of the gun.
You'll notice a circular "cap" on the end of the barrel that is part of the 2-piece barrel unit (at that time). The barrel is simply a steel tube threaded at one end to fit in the frame and the "barrel" you see is a machined steel shroud. The barrel tube is threaded onto the frame and the shroud is slipped over it. The shroud uses locating lugs to position it solidly onto the frame. The barrel is screwed down into the frame with a special tool, with the flash gap set (approx .004" on mine). The cap is also a tensioner that keeps tension on the barrel and seals up the unit.
This same barrel system was used on the Model 619/620 revolvers.
Why this is all a good thing™
As
Sevens pointed out, Dan Wesson has used this methodology for barrels for over 35 years and it's worked out very well. Accuracy is as good, if not superior to standard bored-through barrels.
The other reason is that by going to this construction, along with frame changes, they have eliminated the "flat cut" under the barrel. With the 2-piece barrel, there is no need for the cut because the barrel tube is thinner than the original. This will (should?) eliminate problems with frame cracks under the forcing cone.
Mine does not have the
ball-detent lock-up, but it's easy to see how that would be an added feature to the swing arm. Mine does have the front lockup inside the ejector shroud. I could not tell from the video if the latest model retains that feature, but it appears there is a spring-loaded plunger ahead of the ejector rod in the video.
The gun's frame, but not the grip frame area, is slightly different. I discovered this when I acquired a set of the old Bianchi "Lightning" grips. The Bianchi grips were rubber grips (like Pachmayrs) that extended up to the frame near the rear sight -- essentially giving the gun the appearance of the shrouded-hammer S&W "Bodyguard". They were meant for plainclothes work with the 2.5" Model 19/66's. The grips fit my 19-4 and 19-5 perfectly. But, the newer model 66's frame is slightly different and the grips do not fit properly alongside the hammer or rear sight. I found some minor differences when measuring with a micrometer, especially in the width of the frame and the distances from topstrap to the bottom of the frame where the trigger slot is and the space between the forward frame and rear sight.
If you add up all the modifications, the new model 66 fits somewhere between the old K-frame and the L-Frame, moving closer to the L-frame.
My new 66 has approximately 1250 rounds through it, 450 of which have been Federal, Remington and Winchester .357 Magnum. 200 rounds of Remington .357 Magnum 125gr SJHP were fired through the gun as the last magnums. Accuracy was very good and there were no problems noted with the gun's operation, not even difficulty extracting spent .357 brass.
I can feel the difference in the slightly heavier M66 vs my M19, both with 2.5" barrels and wearing the same grips. The M19 has more pleasing lines to the eye, but does not shoot any better than the Model 66. The M66 actually feels more solid in the hand (the weight I think) and its felt recoil is not noticeably more or less than the M19.
For what its worth, I've had ZERO problems with any of the new S&W revolvers I've bought since 2004. That includes the dreaded Hillary Hole and MIM parts.
