Air gap between barrel and frame-Smith and Wesson 686?

[FrankB]

Ok. I’m as OCD as the next guy, but this one doesn’t bother me. In the photo below, you can see that the upper and under lug are not tight to the frame, but the main section of the barrel is. In my mind, this ensures that the barrel is as tight to the frame as possible. It also prevents scratching the frame as the barrel is torqued down. While it’s visible in the photo, it’s very difficult to see while just looking casually. That’s just my take...

[Wingate's Hairbrush]

BLUF: Very slight gap or space top and bottom of the barrel shoulder where it meets the frame is normal and to design.

Detail:

Modern S&W barrels for these models have the threads on a slight "pedestal" or boss. When the barrel is screwed in properly and to top dead center, only the boss mates with the frame. The upper and lower portions of the barrel fit closely enough that to the naked eye the clearance isn't easily seen; close scrutiny including the use of a light -- as in this thread -- reveal the gap. There are the typical manufacturing variances and some are more easily visible than others, but they're all there. They don't affect function.

[Pol]

Modern S&W barrels for these models have the threads on a slight "pedestal" or boss. When the barrel is screwed in properly and to top dead center, only the boss mates with the frame.

Do you know why they do that?

[Wingate's Hairbrush]

Do you know why they do that?

On this question I'll rely on my betters. Member Protocoll_Design over at the S&W Forum posted this:

All the factory barrels have some gap. The back of the barrel is faced off except for a ring the size of the central barrel area. This gives an even contact with the frame around the threaded part. It serves multiple functions.

It makes the barrel essentially free floated so it doesn't change point of impact as it heats up during firing, keeps visible areas of the frame from getting scratched during assembly, and makes a good place to make minor adjustments when setting the amount of crush fit. This gap is normally .002 to .003...

[willie]

I disagree that the gap is normally 2-3 thousands. 6-7 is more like it. I have seen large numbers at .008.

[FrankB]

This guy seems to honestly believe his revolver is defective, and he even sent me running for my feeler gauges when I watched the video.
https://youtu.be/uB3mkaQfEjs

[Pol]

On this question I'll rely on my betters. Member Protocoll_Design over at the S&W Forum posted this:

#2 and #3 make sense given Rufus and Skeeter are working on the S&W assembly line rather than the qualified gunsmiths of old.

#1 not so much. The older S&Ws (without gaps) are way more accurate than the new ones.

[AdioSS]

Dangit, now I’m going to need to check this on mine when I get home...

[willie]

Check something else. You might discover that the front of your cylinder in not square, or that the rear of the barrel is not cut or filed square, or both, and despite what I tell you, you will not believe me when I say the damn gun is within specs this way, and you really might get mad when I tell you your feeler gauges are all fucked up too. And it makes no difference anyway.

[Hambo]

The older S&Ws (without gaps) are way more accurate than the new ones.

If so, it's more likely that some combination of the barrel-cylinder gap, forcing cone, throat diameter, and rifling are the problem.