Bolt-circle diameter of a 629 vs 627

[mcb]

So they are both N-frames but if I remember correctly the diameter of the circle passing through the center of the chambers on a 627 is larger than a 629. This also required the axis of the barrel to pass through the frame higher too. I can't seem to find those two dimensions. Would anyone have them? Are the other 6-shot N-frames (27, 610, 625, 57 etc) all on the same diameter at the 629? I assume all the 327/627/929 are all on the same. Thanks ahead of time.

 

[Alk8944]

You are talking about the distance from the cylinder axis to the bore axis? The reason you do not find measurements is because there is no difference! Any N-frame frame can be built into any caliber, .357, .41, .44, .45 ACP or Colt indiscriminately.

The term "bolt circle" refers to auto wheel bolt patterns, specifically the diameter of the circle around the center point of the wheel/axle axis, which passes through the center of the wheel stud holes. It has no place in reference to firearms!

 

[mcb]

I was at work when I wrote this, was hoping for a quick reply as I was playing around with some ideas in CAD.

I agree that for most N-frames that radius from the center of the cylinder to the center or the chamber (or twice that being the"bolt-circle" diameter) is the same for all the 6-shot N-frames but I was pretty certain with the 8-shot N-frame they moved the chambers out. Obvious the barrel had to move up in the frame also.

So when I got home tonight I measured my few N-frames. My 625 and 610 (both 6-shots) are nearly identical with the "bolt-circle" diameter being 1.091 in the 625 and 1.086 in the 610, a difference of only .005 inch.

My 627 (8-shot N-frame)on the other hand was measurably larger with a diameter of 1.162 which is ~.073 larger than my two 6-shots N-frames.

This question started with the idea that it should be possible to make 7-shot 10mm Magnum on the N-frame. Not that such a gun make any sense from a profitable product point of view...

 

[Darkenfast]

I remember reading about this in one of the gun magazines when the 8-shot Smith and Wessons first came out. Seven-shot N-frames had been done, but in order to get a capacity of eight, safely, the line of the bore had to be moved out from the center of the cylinder just a bit. Unfortunately, I can't remember where I read it.

 

[rwsmith]

Well....

.....

The term "bolt circle" refers to auto wheel bolt patterns, specifically the diameter of the circle around the center point of the wheel/axle axis, which passes through the center of the wheel stud holes. It has no place in reference to firearms!

Can you tell us what you would call it? I'd call it a "hole circle". Bolt circles aren't limited to car wheels. Flanges have bolt circles also, as well as many other parts of machinery. And some parts have just plain old "hole circles"


PS: The dang bad word filter won't let me spell ***le' without doctoring it up.

 

[BLUEDOT37]

I remember reading about this in one of the gun magazines when the 8-shot Smith and Wessons first came out.

I must have read the same one, & can't find it either on my PC (I scan in interesting articles), but the OP is correct in his recollection. Not sure what Alk8944 was getting at.

.

 

[steelslaver]

Actually you wouldn't have to change the frame. You could also drill and rifle the bore of the barrel .0365 up of center. If they moved the hole in the frame up the barrel shank would be up tight against the top strop or the top strap might be relieved a little bit. Don't have anything besides 6 shooters N frames myself.

 

[Hondo44]

The 627 8 shot does have a larger chamber bore ctr radius.

The frame hole for the barrel was drilled higher up in the frame which made the extractor rod center line farther from the bore CL. That's why barrels and cyls won't work in a standard N frame.

The 1st was a model 627 Lew Horton Special in 1998, then the 27-7 for Bangers Dist. Special in 2000 and both built special in the Performance Ctr. These were followed by several other 'Special' versions. Made on the new N frame with frame mounted floating firing pin, which also had to be positioned higher in the frame hammer channel.

There's no term police but Bolt circle is an oxymoron as applied to a firearm because there are no bolts or bolt holes on a firearm.

 

[mcb]

Got distracted by other distractions.

Here is what I got using the measurement of my 610, 625, and 627 while thinking about a 7-shot 10mm Magnum N-frame.

This is a traditional 610 10mm cylinder
There is .120 inch between chambers and .105 between a chamber and the outside of the cylinder.

This is a 7-shot 610 10mm cylinder on the same "bolt circle" as the 6-shot N-frame.
There is .048 inch between chambers and .105 between a chamber and the outside of the cylinder.

This is a 7-shot 610 10mm cylinder on the same "bolt circle" as the 8-shot 627 N-frame
There is .079 inch between chambers and .069 between a chamber and the outside of the cylinder.

No image but for reference a 627 has .062 between chambers and .092 between the chamber and the outside of the cylinder. It seems that a 7-shot 10mm Magnum build on a 627 frame could be possible but you would have to do some FEA. The slightly larger chamber diameter and slightly higher pressure are going to add up to quite a bit more stress in the cylinder. It would need some careful testing.

 

[jaymoore]

Can you tell us what you would call it? I'd call it a "hole circle". Bolt circles aren't limited to car wheels. Flanges have bolt circles also, as well as many other parts of machinery. And some parts have just plain old "hole circles"....

The usual machining term would be "bolt hole circle" or "bolt circle". There's even a FANUC "G code" for generating said. G70

Easier to reference, even if the holes won't be filled with "bolts".

 

[Tom S.]

Can you tell us what you would call it?

Chamber center line or chamber center diameter?

 

[steelslaver]

For reference an L frame 44 mag cylinder has about .045 outside walls.
So, I would think that the .069 should be good. A 10mm or .40 would not need quite the wall thickness of a .429 to hold the same pressure.

On the chambers remember this. With steel piping the pressure rating for pipe of the same wall thickness goes down a the ID increases. Or better put, as the pipe size goes up the wall thickness needs to go up to keep the same pressure rating or scheduled. Piping schedule mean it is rated at schedual x 1000 for P/S (P=Design Pressure and S=Allowable Stress) To make schedule 40 3/8" pipe needs a .091 wall and a 1/2" pipe 0.109. I have spent a LOT of time pressure testing piping.

 

[mcb]

Thanks steelslaver. I was wondering how thick a 44 cylinder was. Being the L-frame it is probably even thinner than the N-frame 44's.

It would be really cool to get a 7-shot 10mm Magnum N-frame but I am not sure S&W would ever do it and I don't have the tooling or expendable income to custom build one. Would be sweet though.

 

[Nemo288]

I have been thinking quite awhile about a similar project that I wish S&W would do and that would be a 6 or possible 7 shot .445sm in the X frame.
8 or more .357 Max rounds might fit as well.
No one has made a nice revolver for the 1.6" rounds that started the .45 and .50 supermag madness since Ruger dropped the 357max
and the original Dan Wesson went out of business while making the big 445 (and others).
The X frame is obviously ideal for re-introducing both the 357 and 44 supermags.
They could even satisfy the dozen or so .375 and .414 shooters out there!
How many rounds the cylinders could hold would be interesting to see.
The BFR can be made in 445 but the cylinders are obscenely long as they are designed for the 444.
Gross and ugly IMHO.

I have also been trying without success to convince Bighorn Armory to downsize their 500 S&W carbine to .445.
T'would be perfect if a tad expensive. They did just do a .460 S&W version.
Going down to the 44 would be a minor challenge. I would not mind the heavier barrel.

Welcome to the forum and thanks for bringing up a thought provoking idea.

 

[reddog81]

7 shot 10mm N frame would be great but I'd be happy if they brought the 610 back.