New 642-1 PC Cylinder Gap

scruffy · Aug 5, 2019

Picked up a NIB Performance Center Model 642-1.

The good: Trigger is noticeably lighter and smoother than my other J-frames. It shoots well and I can get better groups with it at 10 yds. than my 442 or M60-3. Barrel is not canted and the grips are very comfortable.

The bad: Barrel to cylinder gap is a consistent .012" as measured with a good set of feeler gauges. I shot FMJ and JHP ammo so didn't notice any spitting and the forcing cone is cut sharp and even with no burrs.

Not sure if I should call S&W to return it to have the B/C gap set to .006". Guess I was expecting a closer to ideal tolerance from a Performance Center gun.

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ContinentalOp · Aug 5, 2019

FWIW, I think that would fall within S&W specs, so they wouldn't change it under warranty. Maybe as custom work.

Personally, as long as the gun is shooting well, I'd probably leave it as is.

Just my opinion.

Chino74 · Aug 5, 2019

I used to worry about my BC gap on my Ruger SRH Alaskans a healthy .080 to .010 both of them are in this range end shake .040 to .050 if it gets too hammered & the end shake increases I'll send it to Ruger otherwise they shoot fine., I'd say same with the S&W. Shoot it. End Shake is more important anyway, when that gets too much time to send it to the factory.

JayFramer · Aug 6, 2019

Sorry but the Performance Center knows EXACTLY what they're doing.

If the gun showed up with a .012" gap, it was for a reason.

Just shoot it.

Hapworth · Aug 6, 2019

Politely, I don't think today's Performance Center knows exactly what they're doing, compared to earlier iterations. They do know about getting their stamp on ordinary production pieces and getting them out the door, though...

OP: .012" is within current S&W specs, albeit barely. Whether or not it's an issue in your gun comes down to how well it shoots, and can that tiny barrel with the long gap get your preferred defense load traveling at a speed adequate to yield its designed performance.

Only testing those loads in that gun can confirm this.

After that, if .012" won't do, I'd contact S&W and explain your situation to them. I don't ordinarily recommend S&W for repairs or gunsmithing these days, but assuming you bought new they might get you to your preferred gap under warranty, and some top gunsmiths wont pull barrels on the aluminum Js for risk of frame bending (whereas S&W appears well-equipped to avoid that and it's on them if it does happen), and they have plenty of replacement barrels to choose from whereas a gunsmith won't (I don't believe S&W does barrel setback in cases like these, but simply mounts a new barrel with narrowed gap -- I've been through this twice with them).

scruffy · Aug 6, 2019

Apparently the Performance Center didn't get the message that they are infallible. It's manufacturing and sometimes things do get out that should not. It happens in every industry.

Called S&W CS this morning. Very prompt and courteous service. Bottom line is the 642 is back on it's way to the mother-ship. After explaining my measurement of .012", I was told with no hesitation that top of the allowable tolerance for the B/C gap was .010" and the CS rep emailed me a FedEx return label before the phone call ended.

Hopefully I'll get it back corrected and as new in a reasonable time.

Hapworth · Aug 7, 2019

scruffy said:
Apparently the Performance Center didn't get the message that they are infallible. It's manufacturing and sometimes things do get out that should not. It happens in every industry.

Called S&W CS this morning. Very prompt and courteous service. Bottom line is the 642 is back on it's way to the mother-ship. After explaining my measurement of .012", I was told with no hesitation that top of the allowable tolerance for the B/C gap was .010" and the CS rep emailed me a FedEx return label before the phone call ended.

Hopefully I'll get it back corrected and as new in a reasonable time.

Good to hear. A few years ago when I was in the same boat as you and contacted S&W, they also said .10" was the b-c limit, but so many members reporting here have gotten the .012" answer that we've all presumed it to be the new spec.

Perhaps it just comes down to which customer service rep you get; maybe you got the one I did -- they didn't hesitate to correct gap under warranty on two new Js I had that came in at .012" and .014".

Hope all goes well. Inspect your pieces closely upon return -- as if you were buying them all over again -- and let us know your results.

Rock185 · Aug 9, 2019

Within my humble experience in buying S&Ws for a very long time, B/C gap has increased over the years. As a result of this discussion, I just checked a 642-1, purchased new several years ago. Sure enough, the B/C gap is .012". I have little doubt that it is just quicker and cheaper to produce S&W revolvers with wide range of B/C tolerances, than to try to keep B/C gaps somewhere around .006", or preferably less as I would prefer. If the spec. is .010" or less, does anyone inspecting really care or actually check? My 642 functions as it should, but if it was a gun I cared very much about, I would be very dissatisfied with such a wide B/C gap. FWIW, a copy of an old S&W factory revolver repair manual I have indicates B/C gap should gauge .004"-.008". Kuhnhausen's S&W shop manual, last copyright 1990, indicates S&W factory clearance ran between .003" and .006". Take your pick, but both a lot tighter than what many are reporting now days.....

As to Performance Center firearms, more and more it seems to me the PC logo indicates non-standard features, but not greater precision in machine work or more precise fit of components than might be expected in any similar regular production model. I've owned a few PC guns from about the late '90s. I believe those that have owed PC guns from that era would agree that we're not likely to see firearms of that precision and overall build quality from S&W again. Is there an actual PC anymore, or is the "PC" just another line in the main factory?

slabside2 · Aug 9, 2019

Just checked my 442-1 it's. .004

Gene L · Aug 10, 2019

You guys got me paranoid, so I measured the BC gap on my three S&W revolvers, a 1972 or so Model 28-2 (009) a Model 36 about the same era (.008) and a new 442 (about .008 or .009, can't remember). So I'm relieved.

Toddlars1 · Aug 10, 2019

Scruffy, I have a NIB PC 637, just measured the BC gap at .004 so I guess I got lucky

mtnwinds · Aug 10, 2019

For what it's worth, I just picked up a new 642-2. The BC gap is .005 for all chambers measured on the right side and .006" for all chambers measured on the left side. So the barrel is .001" out of square with the cylinder. Doubt I'll ever be able to tell any difference when shooting it.

jaymoore · Aug 11, 2019

mtnwinds said:
For what it's worth, I just picked up a new 642-2. The BC gap is .005 for all chambers measured on the right side and .006" for all chambers measured on the left side. So the barrel is .001" out of square with the cylinder. Doubt I'll ever be able to tell any difference when shooting it.

More probable is that the barrel's rear face cut slightly off plumb, but as you note, it's likely academic.

And, just to throw another variable into the works, my very first 25-5, purchased new in the early '80's (an N prefix revolver) had a cylinder that had NO BC gap about 1/3 of the way around, going up to a max of about 0.005". Scrubbed the bluing off part of the cylinder face and wanted to bind some in DA after getting just a little dirty!
Seems the cylinder face itself wasn't cut true. My solution was to mimic the S&W fitting method of the time by filing just a tad off the rear of the barrel. Worked well, think the max gap ended up at about 0.010", but i swapped that revolver off, sadly, by the late '80s for i forget what. That 25-5 also taught me the value of measuring cylinder throats, as they were huge. It DID like the old WW swaged 0.256" dia. 255gr lead hollow base bullets very well!

gumpys · Aug 17, 2019

scruffy said:
Picked up a NIB Performance Center Model 642-1.

The good: Trigger is noticeably lighter and smoother than my other J-frames. It shoots well and I can get better groups with it at 10 yds. than my 442 or M60-3. Barrel is not canted and the grips are very comfortable.

The bad: Barrel to cylinder gap is a consistent .012" as measured with a good set of feeler gauges. I shot FMJ and JHP ammo so didn't notice any spitting and the forcing cone is cut sharp and even with no burrs.

Not sure if I should call S&W to return it to have the B/C gap set to .006". Guess I was expecting a closer to ideal tolerance from a Performance Center gun.

[/IMG]

Honestly if it is not spitting and you are getting good accuracy out of it, why even bother worrying about it. Shoot and enjoy it.

Sent from my LG-H910 using Tapatalk

scruffy · Oct 8, 2019

Back from the mother ship. New barrel with a consistent .004" B/C gap (reduced from .012"), new crane (there was a slight internal catch on the ejector rod when releasing it) and re-finished and re-laser engraved the frame (small tool marks side of the top strap). Took a while, but very pleased with the results. Put 50 rounds through it today and it very accurate when I did my part. Shouldn't have left the factory that way in the first place, but S&W stood behind their warranty 100% and made it right.

Toddlars1 · Oct 8, 2019

Glad to hear that

Luvmine · Oct 9, 2019

Glad to hear they did the right thing.

bigfatty · Oct 10, 2019

Glad to hear it's all good! IIRC, mine is also .004. Summer shutdown is a drag, two months is heading into Taurus territory. I've been lucky with my J frames, but I've had to send back or refuse A LOT of K and L frame.

New 642-1 PC Cylinder Gap

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