I recently added a Model 66-8 to my collection. Looks and feels much like my 2-1/2 inch Model 19. First (and every) outing to the range I get anywhere from 18 to 30 shots out of the 66 before everything is jammed up tight. Rubber mallet tight.
Below are some close ups of the cylinder fore-ends and the rear of the barrels on both guns. The 19 has a nice, elevated gas ring that is shielded completely by a plate of sorts on the rear of the crane, and the rear of the barrel shows a flat cut on the bottom to allow the crane to close and lock up.

The 66 appears to have eliminated the gas ring and the rear of the crane has only a partial plate shielding the cylinder axis. This appears to have been done to eliminate the flat cut on the barrel but the problem here is that the recessed area sits directly under the rear of the barrel and every time the gun is fired the hot gases blow all sorts of junk right past the partial shield and deep inside the cylinder. No wonder it keeps jamming.

Unfortunately the model 66 requires complete disassembly of the cylinder after every outing. There has to be a better way!

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This seems to be an accurate assessment of the situation. I agree - there has to be a better way.

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protocalldesign.com

OK I’ll go and say it they don’t make um like they used to.

I think the reason for the change to the forcing cone part of the barrel (flattened area vs. full round) was to prevent barrel cracking.

It was in the flattened area that most all of the K-frame 357's failed. Hence, the recommendation to not shoot magnum rounds full time in the older guns, and to stay away from 125 grain magnum loads popular back in the day.

The real fix is the L-Frame for full house loads all of the time.

Gunsmith Time .
I live in Louisiana so I would take it over to Clark Custom Guns , them boys know a thing or two about S&W's .
Check your local area and ask for references .
Gary

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Certified Cajun
NRA Member

Welcome to the S&W Forums. You did not mention what ammo is causing your new Model 19-8 to lock up.

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VCDL, GOA, NRA

Is this common in the new 66/19s? Makes me rethink buying one if it is.

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FiveG

Had an issue with my new SW 500 just like yours. It’s common for the ejector rod to come loose and bind the cylinder. I sent it to SW for warranty repair and on the invoice it said they replaced the bushings. Has worked fine since then.

Definitely send it back to SW.

Sending it back won't help on this one. That's the way it was made to begin with.

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protocalldesign.com

Welcome to the forum and sorry to hear about your problems with that new gun. I would send it back for warranty work.

S&W gives excellent service. Unfortunately there are times when you need to send your gun in but I've always had luck getting mine back working correctly.

All my guns have been modified. I let S&W know that they are for competition and they always leave my trigger work alone as long as that's now what is causing the problem. Otherwise they replace and charge me for the new parts. That's reasonable.

Send it in. Good Luck. It's a shame that a new toy won't work right out of the box.

What you describe is a 'potential' cause of the problem you are seeing, but not the only one, In any case having the revolver tie up completely after no more than five cylinders full of ammo is unacceptable. I would contact factory customer service, who will likely send you a prepaid shipping label to get it looked at.

The good news is you still have your model 19 to launch .38s/.357s. The better news is you have made your first post 9 years after joining. Welcome and sorry for your troubles.

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Alan
SWCA LM 2023, SWHF 220

What kind of ammunition was binding up the gun?

The gun design by itself is not the problem. I've gotten lax about gun cleaning and my 66-8 works great when filthy.
Attached - 66-8 with many cast bullet rounds fired.

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Any and all ammo causing it. Locks up fastest with factory 357 loads.

Back to the factory for warranty work.

Check the barrel / cylinder gap.

Metal expands when it gets hot. With a revolver the front of the cylinder gets hot from rounds being fired shrinking the b/c gap. If the b/c gap is tight when the gun is cold the expansion of the cylinder can cause it to rub against the back of the barrel creating the problem you are describing. This is not a uncommon problem. There are two easy ways to check for this problem;

1. Next time you go shooting when your revolver starts binding sit the gun aside and let it cool down. After the cylinder gets cold try shooting it again. If the gun repeats the problem of functioning fine until the cylinder gets hot then you have found the culprit.

2. A more accurate method is measure the b/c gap with a spark plug feeler tool. Minimum gap is .003”. Be sure to measure the gap from both sides of the gun. It is not uncommon for the back of the barrel to be cut unevenly. I had a revolver that measured .003” on one side and only .001” from the other!

This is a quick easy fix for a gunsmith. There is a tool that will square the back of the barrel to open the gap. At the same time have the gunsmith recut the forcing cone on the back of the barrel. It will take a gunsmith all of 10 minutes to correct the gap. I shoot a lot of cast lead bullets which results in a lot of fouling building up on the face of the cylinder. Personally I dislike cleaning guns so sometimes I clean them once during the year usually during winter cabin fever. Generally.003” is the tightest recommendation. I have the b/c gap on some of my revolvers cut to .008” as I demand that my revolvers continue to function even when dirty.

Keeping in mind that I'm just guessing, I would have a real gunsmith cut me a light forcing cone just to remove/clean-up those 'inside' edges....

IMHO,
J.

Did you clean out really well behind the ejector star?

Do you lube it up real good behind it?

That might me causing it. My 686-6 used to bind up all the time until I backed off on lube to a drop.

Hi,
Thanks for the input. The problem is not the cylinder gap, the forcing cone or the ejector star. It is definitely the crud that is blown into the center area of the cylinder. When the gun jams up, and I am finally able to swing the cylinder out, the cylinder cannot be rotated at all on the ejector rod. What I have to do is remove the cylinder/crane assembly and soak it in a plastic tub of solvent. When I can start to turn the cylinder I do a complete tear down on it. The amount of soot, lead, burnt powder, etc. is what locks everything up. Once the internal cylinder parts are cleaned and lubed everything works fine until the next string of shots is done later.
I have a fair number of S&W revolvers (10, 14, 19, 22, 25, 36, 37, 29, 57, 58, 649) that date to the 60's thru 80's and this is the only one that has ever done this. I would never trust this one as a defense gun.

Send it back to SW or take it to a gunsmith. Get it fixed and then report back. Thanks.

Check with a feeler gauge the gap between the cylinder and barrel?
Your shooting leadcast and jacketed bullets and it still happens.

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Plant garlic in the fall

It is definitely not the cylinder gap. Once I manage to open the gun the cylinder will not rotate at all. I can understand if it would not rotate when the cylinder is closed but once I manage to swing the cylinder to the open position the cylinder is frozen solid and requires complete disassembly and cleaning to resume normal functioning (for the next 20 or thirty rounds)..

Don't mess around with it.

Call S&W Customer Service - they will pay for shipping both ways.

Get it fixed, and enjoy the gun.

Recently I had a new 19-9 fixed under warranty, it took about two months from shipping out until returned.

When I asked about having some simple non-warranty work done on an 18-3, they said it would be six months.

@Rachel33189: I would repost this in the Gunsmithing part of the forum, those guys do not automatically search other sub-forums looking for interesting questions to answer, If the problem is common, someone in that forum might know, but if this is a recently made gun, they may not.

There is some reason why more crud is generated in your revolver, and going where it should not be. It can't just be the odd gas ring design. Some dimensional tolerances may be off, or something else. The clue is that the use of 357 ammo causes is more quickly (higher pressure round or more heat).

If the cylinder gap is too large, more gasses carrying crud may be escaping into the area between yoke and cylinder (for example). Maybe it is worth it to measure it, even if it is not the main or only cause. Minimum, maximum, both left and right side. Feeler gauges are cheap.

If you remove the yoke and cylinder assembly, and then separate the yoke from the cylinder after some small number of rounds (24~30), you should be able to take a pic, post it, and someone can tell you whether what you are seeing is normal or not.

On older .357-rated magnums, the gap between the forcing cone and the cylinder was usually smaller from the factory compared to .38 spl guns, and for good reasons. Not sure if that is still the case on a modern 66-8.