please delete

Maybe that's their new rifling system I heard about.

I have read that they quit cutting rifling and went to a new way of doing it.

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Eccentric old coot

How does it group?

Lol, get outa here! Yes, as Iggy said, that's that 'new fangled' rifling you're seeing. You do know about rifling, right? (Of course you do).

There are many ways to put rifling in a barrel. Some old. Some new. I think Iggy is referring to a new way S&W is doing it. I believe they're casting the rifling in, MIM, fashion, or maybe it's etched chemically or electrically. I'm not sure. They're doing something different, no doubt a cost savings.

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~ S&W aficionado in training ~

From the photo: it looks as if the end of the muzzle shows where the lands and groves are extending outward. Most of my modern S&W have a similar appearance to them. It doesn't look pretty. I have inquired on Brownell's website to find the proper muzzle re-finishing tool to clean up the muzzle end. The kit was on back order. I'm still waiting.

What was the Physics question? Standing by with my slide rule.

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~ S&W aficionado in training ~

It's to counteract coriolis effect (earth's rotation) on bullets in the northern hemisphere; guns sold down under have the flat spot on the bottom of the barrel. You have to look close sometimes to see it, the amount depends on how much coriloc torque they had to dial in on the rifling machine.

No flat spot, the crown of the barrel must be straight and true or the bullet leaves the muzzle in the wrong direction.

Yes, it looks odd to me too. My 637 looks like it needs a new crown, but it shoots great.

David

It's a result of rifling formed by Electro Chemical Machining, a variant of EDM developed by S&W. Rumor from the factory has it that when the process was first developed it produced barrels so consistent that fired bullets could not be determined which barrel they came from so the ATF insisted that S&W do something to degrade the finish to produce random markings on fired bullets.

As for accuracy, I have a model 620 that produces so many cloverleafs in practice that I put a 2 power handgun scope on it to try and test it's ultimate accuracy. I then spent 6 weeks practicing 2 times a week to develop better trigger skills in Single Action. When I felt I was up to the task I managed to shoot a 7/8 inch group at 50 yards. BTW, I was using 130 grain American Eagle FMJ 38 special, so that result was with the bullet the extra bullet jump in the cylinder. IMO that bit about shooting 38 specials in a 357 Magnum is Urban Legend and nothing more. I also learned that it takes a lot of practice and ammo downrange to shoot a handgun or rifle near it's ultimate accuracy. I probably put 1500 rounds downrange working up to that result and I'm pretty certain that my 620 was still capable of more accurate results, probably under 1/2 inch at 50 yards. Note, the model 620 was a 7 shot L frame with a steel frame and a 2 piece tensioned barrel in a semi lug profile similar in appearance to the 686 Mountain Gun.

So, yeah, these new fangled "cost saving" ideas seem to be capable of producing excellent products and accurate revolvers.

Do you really think S&W is looking for ways to make their revolvers MORE costly to produce?

I don't doubt the new rifling is capable of high accuracy. I think it's great, and I applaud S&W for their efforts. It's a good day when cost cutting measures also have a functional benefit. That's what all those engineers are paid to do.

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~ S&W aficionado in training ~

Hardly "new". S&W has been using ECM for rifling barrels since 1993. I believe it took a while to change over, so conventional rifling (broach cut) and ECM were used concurrently through appx 1998.

It's my understanding that the PC still uses conventional rifling while the production guns use ECM.

That shouldn't be interpreted as the one type being superior to the other. ECM is less expensive in a production environment, but yields superior results manifested as smoother, more consistent rifling. A win-win situation. Since the PC is a small batch production facility it may just be more economical to do it the "old fashioned" way.

I think this whole thing about leading and ECM rifling is misconstrued. There are too many other variables to consistently lay any leading problems at the feet of ECM rifling. Iggy kind of proves that point - I'm sure that ECM rifling was prevalent for a long time before anybody realized that S&W had changed processes and the leading issue only raised its head once it became common knowledge - whereas you never heard of any leading issues prior - even though the new process had been in use for some time.

Adios,

Pizza Bob

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NRA Benefactor Member

I only have one new PC, a 460 XVR, but it appears to have ECM rifling in it. Maybe someone else can confirm?

.

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Waiting for the break of day

VT, you're a Devil! I think one of the posts following yours' actually took you seriously.

Hankster

Well done. Well done indeed.

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Forum consigliere

not really "physics", but just plain simple machining ( crowning) of the end with two different levels of thickness, a 'land' and a grove' ',, makes the eyes do funny things...its when damaged or cut on an angle, will 'prerformance and accuracy' suffer.......... many different types, styles of crowns out there, too many to sit and type out or try to "splain why"....

oh and the "coriolis effect" does NOT take place until the external ballistics reached, before 'terminal' ballistics take final effect.

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dan
NRA Benefactor,PMA

Daddy always told me if you can't dazzle them with brilliance then baffle them with bullpucky !
I like your physic's! Sounds quite logical.

Gary

Have the prices on any of the guns come down? Most of the cost cuts turn into more profits for the company rather than savings to the customer.

It's also one of the reasons why S&W hasn't declared bankruptcy and closed it's doors like many of it's competitors. In the private sector making a profit is important.

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~ S&W aficionado in training ~

Guess it's a good thing you point that funny-looking muzzle AWAY from your puzzled eyes when you shoot it. You CAN look at it when you fire it, but only once, and then it's very hard to share the results.

Ed

.

.

I wanted to amend this to add that I just bought a 627PC, 5" one-piece barrel, & it does appear to have the old style rifling (broach cut). Nice sharp lands/grooves. The gun shop also had a 327 TRR8 in the case that I looked at & it's two-piece barrel looked to have ECM rifling, as I suspect all two-piece do. So maybe the Performance Center is still using this style on all (?) the current one-piece barrels still.

.

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Waiting for the break of day

I think the airweight J frames like the 642/442 price did come down. They use MIM barrels and ECM. Take a look at the muzzle on one of them. Very strange looking. You can see the MIM mold mark at the 6 o'clock position and the rifling looks very uneven at the "crown" area, I used "" around crown as it looks like the barrel does not have one. Shoots well, but not aesthetically appealing.

...or serve as an offset to increased production costs.

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NRA Benefactor Member

Put your boots on boys. It's getting real deep here....

Odd number (5 in this case) rifling is always going to look "out of round" when viewed at certain angles.
It also makes measuring the groove dimension difficult.
On the other hand it produces just the right amount of wobble to correct for the movement of the earth's magnetic poles.

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Nemo

Dont forget for baricenter compensation that keeps the barrel synchronis withe the Earths tilt.
Couldnt help it.
Jim

I think it has to do with keeping the timing of the gun in sync with sidereal time so that the gun's timing will be accurate regardless of what time zone you are in. Of course, this gives the added benefit of compensating for the Earth's position along the ecliptic, except on Feb 29th, leap year. And as everyone knows, this is when baricenter compensation is most critical.

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Rachel
Grande Torina