I've been having issues with arthritis in my hands lately (yeah, I'm old) so I took a FastFire3 off a 686+ and put it on my 617 so I could go shoot. Put 3 rounds in the target, all very close to POA. No sight adjustment needed. The 686+ and 617 look like they have the same frame but mine were made years apart. This is either a real coincidence of really good machining consistency. Thanks S&W.

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Foster Positivity.

CNC machining is very consistent. The 686 is an "L" Frame, and the 617 is a K Frame. But the rear dimensions that hold the sight must evidently be the same specs.

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H Richard
SWCA1967 SWHF244

I believe the L, K, N and X frames have the same rear iron sight channel dimensions.

Among other differences the J frame sight channel is narrower and shallower and does not enjoy the three tapped holes (started in early 90s?) of its big brothers.

However J frame critters can enjoy a Fastfire:



It does require two new tapped holes:

CNC programming will get you the same until the cutters wear down and the machine should tell you maximum specs have occurred.

That depends very much on the machine! And whether it's programmed to gage every cut. Which raises machine time quite considerably and, thus, costs. CNCs aren't magic. Often quite ornery critters....Especially when dealing more difficult to machine materials, which barely applies to anything revolver oriented, even titanium and garden variety stainless, so not much excuse there. But I have seen quite a few S&Ws, including 1990s PC revolvers that show cutter failures, often fairly noticeable. In their defense, I think the internal milling (areas that most folk never see) has improved in the past 20 or so years. Some of those pretty 1970s revolvers have the most atrocious looking internal work!

When I was building new CNC machines we could offset the machining errors inside the control. They actually burn the offset into the memory. If the cutter has an error because of the offset weight of the milling head they can offset the error to the millionths. This is why there doing mim parts today. Leave it a tad larger and let it wear in by itself. That’s why the action and trigger get better in time.

I built one 86” chuck lathe with a 95” stroke ram(cutter). With a 95” stroke ram the over hung weight and under slung weight is different as the ram moves out of the saddle. There’s only so much we can do mechanically. This is where the offsets come into play. The machine was boring cylinders for 200 ton presses. The lathe was spinning a 56,000 lb cylinder at 100rpm on the last finish bore.

Hey, Bill, that IS big!!! We just do wee turbines.

If you guys think SW had/has machine marks go find a M1 Garand from around 1/42 to 5/43...LOTS of machine tool marks on the receiver...including the heel, I have a SA that has a line on the heel where the mill worked it...its a 4/42 rifle.

I AGREE. I HAVE NO-DASH, 8 3/8" SPECIMENS OF BOTH MODELS. THE REARMOST FRAME DIMENSIONS APPEAR TO BE IDENTICAL.......

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'Nam 1968-69.DAV,VFW,NRA Inst.

If you think your Springfield built Garand is bad, look at some WWII Winchesters. Apparently they decided that losing money on military contracts like they did in WWI wasn't such a good idea, so they decided "pretty" was "out"! I only have 2 correct examples of pre-"Win-13" rifles, but they're both covered with rough machining, grinding and file marks- otherwise they're pretty nice! (The Win-13s I've seen aren't nearly as bad, but they're very late WWII.)

BTW, does anybody know where the primary locating planes/points are on a S&W revolver frame? In other words, from where do most all the other dimensions originate?

Ithaca 1911A1s made for military during WWII are known for machine marks especially on frame. Doesn't effect function and makes them somewhat unique.

My Chinese norinco sks has crude machining plus its loosely fitted parts. When first cleaning it I doubted it could shoot. But it’s flawless in operation.

The biggest lathes I built were 124” & 144” chucks.

This reminds me of robotic welders. Industry speaks of them as if they're the second coming, but I've seen a LOT of poor quality robotic welds. (And a lot of failed and cracked welds)
Of course, they are set up by humans, but I see a lot better quality welds that were done by humans than by robots.

Then again, it seems some alloys just don't want to be welded or stay welded.

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What would Jim Cirillo do?

Gap bed type??? Or what is usually referred to as Vertical Boring Mills? (For no apparent good reason, since they're usually just el grande VTLs.)

Bullard Vertical turret lathes. I built machines that went all over the world for the auto industry and oil industry.

I sent 25 vtl’s”s to caterpillar installed in one building. Not a human on the floor all pallet loader robotics. Cat was way ahead of there time production wise.

As far as s&w once the machining parameters are set they run and clone everything is the same. The mim parts wear in on their own.

When the cutter wears the operator can hit the tool inspection button and it will pull out of the cut for the tool to be indexed. Then go right back into the cut with no line or seam visiable.

I can see s&w making parts popping them out as fast as popcorn.

Pretty fancy machine. Curious what machine that is so I can drool. My little machine does not even have an ATC!

Yes, indeed! Fanciful stuff that I've never seen even in our wee shop. But we did just get a new five axis CNC mill that the mfg. is still setting up. Maybe....Not that I'd run it any time soon. Stuck on the gap bed lathe most of the time lately. But none of the Okumas or Mazak mills, nor any of the more obscure big CNC lathes and grinders have such here.

I have 2 CNC mills, couldn't run without them. However - If you don't do it right, CNC is just a faster way to make scrap.

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