Got my measuring equipment out which is gauge block set,calipers,outside mikes and feeler gauges...to see where the issue might be with the out of square cylinder gap.

Holding revolver as normal and looking straight down the gap now is .011 on left side and .005 on the right side.

The cylinder measures 1.661 in length all around.

Using gauge blocks I find the distance from forcing cone to the back of frame to recoil shield area which is a flat surface surrounding the firing pin measures 1.737 on the left side and 1.733 on the right side. This proves the end of the barrel/forcing cone is .004 out of parallel with the back of frame.

Looking at what appears is a machine ground finish at the end of the forcing cone/barrel...the direction of the grind marks is almost vertical proving it couldn't have been hand filed after being screwed into the revolver frame.

So they must screw the barrel insert in until it touches a gauging point BUT if the end of the grind cut on the barrel end is not square you end up with target .005-.006 gap on one side but wide on the other.

That would make me ask," Is the barrel straight. Is it perpendicular to the back of the frame. And, how common would that be." If the barrel has been removed to true up the cylinder end of the barrel (forcing cone) and then is screwed in out of alignment it will always be out of spec. Uneven gap.

That's my thinking too! You would think they would have checked it on both sides with a feeler gauge!!

Sure it might shoot fine but it isn't like a Smith should be unless it is built in China!!

The barrel can't be screwed in crooked unless the threads in the frame were machined crooked. I have seen a few of those. If it was straight in the frame to begin with, it will always be straight.

It is my understanding that the cylinder gap is usually fitted by hand filing. This can be a very imprecise method, causing the gap to be wider at some parts than others. It's hard to say what happened in this case, but sad they can't do a lot better in this day and age.

No way they hand file barrel cylinder gap. When I have set a barrel back , I used a 90 degree facing cutter from brownells to cut an even bc gap. They probably have it cut to spec on a cnc machine or have some automated process for it.

So just what can we do for 'ya?

Smith no longer makes fine handguns... they make CNC machined parts which people fit together as best they can. As far a I can tell with little or any QC. My new 629-6 had a barrel with a threaded mounting hole which was not 90% to the frame. Frame should have been tossed....

The barrel was not on straight.... probably because the moron that milled the slot for the front sight blade milled it off center. That barrel should have been thrown away.

The forcing cone gap was 5 thousandths on one side and 9 thousandths on the other.

They don realize or don't care that the milling tools wear with use and adjustments change... or someone has a bad day. I tried talking to anyone at S&W that knew what I was talking about.... but no joy.

No more new S&Ws for me. Found a 629-4 Trail Boss that was actually looked at by a gunsmith. Makes a big difference.

If the yoke is slightly out of alignment, (or the shaft that the cylinder rides on)it may do the same thing. I think I have a tool you can get from brownells that measures that and then you “tweak it” to get it right. Shoot it and remeasure

One thing I have noticed as a owner of many smiths from the 1960s and up is that most of these issues were present on many of the older guns as well. I can’t tell you how many older ones have huge barrel cylinder gaps, barrels that are not in perfect alignment with the frame, and yes uneven barrel cylinder gaps. I can find small problems on all of them if I scrutinize them. People let nostalgia cloud their memory(I know I do). I think some of the worst were from the 1970s and 1980s and I have many to look at. Some of the newer ones I have are fitted very well and as shooters are more durable than ever. You will hear many similar complaints on Rugers too. I can find some imperfections on my new 69 as well but damn that gun can shoot. I am not doing anything to it. It will outshoot my favorite 29-2 . Some may can group better but that is about as good as I can hold at 25 yards off a rest.

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People living in the past quite often see things through rose colored glasses. My grandfather sent his Model 19 that he bought in 1971 back to S&W three times before it was right. As much as we all hate factory defects, they happen and they always have. As long as S&W fixes their mistakes, and they always have for me, I'll continue to support them.

Well I'm not a collector of old S&W revolvers over a long period of time. My first Smiths were a M-66 and a 629-2E I got together in a great deal from an elderly neighbor.
This M-69 was my first new purchase and I took a chance on it from good reviews I had read and from some on here.
Now I have had a new Ruger Alaskan come in that was really out of spec and they took care of it.

So after putting 125 rounds through my 69 yesterday it seems to be a very good shooter and the question is if having a now repaired .011 on one side will this cause any long term errosion to the firing cone?
If not I will just keep it as is.

Remeasure after shooting some as some of the parts may “settle in”. There are a lot of torerances in the guns. They are really not as precise as we wish to think.

Having a wider gap will not cause erosion, just more side blast and a bit less velocity. Not dangerous or damaging, just not how it should be.

Looking at how the forcing cone end of the barrel is finished off it would be wasted effort to send it back for a hopefully even gap. The top strap is so close to the top edge of barrel end you would be nicking the top strap to try and file the gap.
They just screw the liner in to torque and whatever high spot on the end hits there set gauge...well there's your "average" gap.

Shoots good so will keep it!

I've seen video footage of a S&W employee applying a hand file to the forcing cone of a revolver, after the barrel has been screwed into the frame. The filing was very fast and appeared to lack the sort of care that we'd all want on a forcing cone. I can certainly see how such apparent ham-handedness on a forcing cone with a file can lead to uneven measurements with feeler gauges taken from various positions.

The big difference is there was no internet you could go on to tell everyone you had a problem with something, so many think there were never any problems before and this is all a new problem.

If I could buy new guns for the same price as old ones I would only own new ones.

Nice shooting .. take away the two fliers and it would be out standing .. my old eyes usually don't allow me the groups like that anymore !!