Blown cylinder chamber - here is what one looks like

[jad0110]

Blown cylinder chamber (correction: expanded chamber) - here is what one looks like

I am posting this as a cautionary tale to those who buy used revolvers.

This is not something that shows up on the Revolver Checkout procedure at the top of the forum. Maybe I'll see if we can get this one added, with a photo or two.

Anyway, I bought a 2" S&W Model 15-2 a year ago, made in 1965. It is one of my favorite carry guns, and apparently it had a blown chamber ever since I bought it and I didn't notice it until my sister tried it out last month .

Whenever I eject spent casing, I do so with the muzzle pointed skyward, giving the ejector rod a good thwack with my free hand to clear the spent cases. I was aware that I was getting a sticking case issue on one chamber, but I always thought that chamber was running just a little tight, similar to my K-22. In fact, I had considered taking it to a local smith to do just a touch of reaming on that chamber.

When my sister tried the gun last month, she ejected the cases with a much gentler technique and couldn't get the case out of that chamber. Not even close. As I pulled the case out, I could sense it dragging on one spot and got that sinking feeling in the pit of my stomach. I new at that moment what the problem was before I even looked.

Sure enough, there it was. A ripple on the inside of an otherwise smooth chamber wall, directly opposite from the cylinder stop notch. Looked kinda like a door ding on a car. The brass itself had swelled into that chamber indentation, which was plainly visible with just the naked eye.

I took the gun to Matt Almeda (http://www.revolverarmorer.com/) to have the cylinder replaced with a new-used one. Such a job can run as high as $200+ (parts plus labor) if a lot of fitting is required. I lucked out and came in at the extreme low end of the spectrum: about $100 for everything!

So the gun is fixed, but I've learned a valuable lesson. In addition to a flashlight and feeler gauges, I now bring along a boresnake or two in a ziplock bag to clean not just the chambers, but the bore as well, if needed.

Learn from my misfortune.

Anway, here are some pictures. The blown chamber is at the top right in the first two pics, and in the far right in the last.

 

[Brian Williams]

Nice report and congrats for the cheap repair.

 

[F1]

"Whenever I eject spent casing, I do so with the muzzle pointed skyward, giving the ejector rod a good thwack with my free hand to clear the spent cases."

Sounds like a method that's hard on the gun. I just give them a good hard shake as I push the ejector rod. That's the way I've always done it.

That ding, it looks like a minor manufacturing defect that nobody bothered with before. Why do you say it's a blown chamber?

 

[MCgunner]

I whack 'em, too, if unloading in a hurry. Don't wanna risk a rim under the extractor.

Never thought to check the cylinders for problems like that, you're right. Hmmm....fortunately I haven't yet been burned like that, but you got off pretty cheap.

 

[Old Fuff]

What you have is called an expanded chamber, rather then a blown one where the chamber wall is fully ruptured. Expanded chambers are much more common then blown ones, and are usually caused by someone trying to handload a regular cartridge into a magnum. An overload causes a dimple where the cylinder stop notch is cut and the chamber wall is very thin.

And yes, I always look before I buy.

As an aside: Someone may ask, "Why doesn't this happen with K-frame .357 Magnums?" The answer is because the Magnum cylinders are made using a different alloy steel and heat treating process. But of course if you overload the .357 you may get similar results. Ruger has seen Blackhawk revolvers with expanded chambers that were caused by someone that went too far with .45 Colt "Ruger only" loads.

 

[hardluk1]

You did not say you asked S&W about a repair. Do you mean that S&W would not have fixed the revolver for free???

 

[Confederate]

I whack 'em, too, if unloading in a hurry. Don't wanna risk a rim under the extractor.

When gun hacks first began reviewing the Ruger Security-Six, they made a big deal about the short extractor stroke and counted it as a downside. They were wrong. The long extractor stroke is fine for the range, where one can easily recover one's brass. But for police and others who may need to quickly reload, the short stroke gets rid of the brass quickly annd prevents brass from being caught under the extractor.

Jad is lucky to have gotten out of it for a hundred bucks.

 

[Vern Humphrey]

But for police and others who may need to quickly reload, the short stroke gets rid of the brass quickly annd prevents brass from being caught under the extractor.

The proper way to clear the cylinder of a revolver is to point it muzzle up, allowing the cases to fall down, away from the cylinder.

 

[Old Fuff]

Do you mean that S&W would not have fixed the revolver for free???

Why should Smith & Wesson, or any other manufacturer for that mater, fix a gun "for free" when what's wrong was caused by something beyond they're control, or in this case someone who fired an overloaded cartridge in it?

Stupid is a condition that should never be rewarded by "free."

 

[rcmodel]

Anyway, the S&W lifetime warranty doesn't apply to 15-2's they made almost 50 years ago in 1965.

S&W only begin offering the Lifetime Warranty for models made after Feb 1, 1989.

rc

 

[messerist]

Forgive me if this post sounds like it comes from an ignoramus...cause as far as what has happened to jad0110, I am. What would actually cause the "dimple?" An overloaded case? Old Fluff said it would be caused by trying to load a regular case with a magnum load? Such as taking brass for a .38 and loading it for a .357? Could someone elaborate? I am hooked on revolvers and have learned alot from the denizens who haunt THR. Thanks for being there. Good luck jad0110 with the new repairs!

 

[Vern Humphrey]

This is what is sometimes called a "pressure event." The .357 is loaded to far higher pressures than the .38 Special. The Sporting Arms and Ammunition Manufacturers Institute (SAAMI) sets a maximum allowable chamber pressure for the.38 Special at 17,000 PSI. For the .357, it is 35,000 PSI.

Now it is possible to load a .38 Special to .357 pressures (that's how the .357 was developed -- using special high pressure loads in a .44 S&W frame revolver.) Using such high pressure loads in a normal .38 Special revolver will damage the gun -- and this bulged chamber could well be an example of such damage.

 

[rswartsell]

The first handgun I ever bought (in 1976) was a Colt Trooper Mk III. I couldn't afford the Python, but I was gratified to read that the Trooper was a strong a revolver as existed at that time.

I was in the Air Force and stationed with the U.S Army (detached, as they termed it), it wasn't at all unusual for soldiers to exhibit a rather irrational hostility towards myself and my fellow airmen. While shooting at a range a soldier offered me one of his "amazing" .357 handloads and I (at age 18) foolishly loaded and shot it. It extruded the primer and locked the cylinder up much to the entertainment of the idiot soldiers watching.

Afterward, that chamber was never the same. Tough to eject spent brass. It then began to "trim" my cases for me cutting a laser-like circle around the brass so that the rear part of the case would eject leaving a neat little sleeve of brass in the chamber. I replaced the revolver with a new example and left the damaged one for trade with the dealer (he was told the whole story).

A hard lesson learned by experience. A Trooper Mk III was a significant portion of a junior enlisted airman's pay. To this day I feel fortunate that fingers, eyesight and skull are intact and sometimes wonder what the soldier had loaded his surprise package with.

 

[rcmodel]

What would actually cause the "dimple?"

On many six-shot revolvers the bolt locking notches are the thinnest part of the cylinder wall because they are cut directly over the center of the chambers. Which is already the thinnest part to start with.

Five-shot revolvers are stronger because the locking bolt notches are located between the chambers in the thicker web sections.

Excess pressure from an over-load seeks the path of least resistance, and in this case, it is the thinnest part of the cylinder wall at the bolt locking notch cut.
The excess pressure stretches the steel at the thin section leaving the dimple.

rc

 

[Old Fuff]

These explanations are as good or better then I might offer. The problem is usually caused by someone accidentally overcharging a case while reloading, or deliberately exceeding recommended charges because they aren't satisfied with the performance of what the book says, and in their dim-witted brain they think that any load that doesn't blow up the gun is O.K. :banghead:

 

[jad0110]

That ding, it looks like a minor manufacturing defect that nobody bothered with before. Why do you say it's a blown chamber?

Well, technically it isn't: as Fuff stated, it is actually an "expanded" chamber as opposed to a "blown" one. That dimple is deep enough that I no longer considered the gun safe to shoot, particularly with +P ammo. Maybe I'm being a little too careful, but then again maybe not. I have to believe that enough +P .38 would eventually turn than "expanded" chamber into a true "blown" chamber. Plus it is a weapon I rely on for serious purposes, so it only made since to repair it. The gun is well worn, and Mr. Almeda lucked out and found a used cylinder with the same amount of wear (as I requested), so the gun still looks "right" too.

And yes, I always look before I buy.

Amen to that, now I always do too. And I hope others take heed and do the same. I actually went back and anxiously checked all my other revolvers; to my relief, all were fine.

Hmmm....fortunately I haven't yet been burned like that, but you got off pretty cheap.

Jad is lucky to have gotten out of it for a hundred bucks.

Yeah, I am lucky! The cylinder required very little fitting to work correctly, and I think Matt said he acquired it for only $50 or so.

On many six-shot revolvers the bolt locking notches are the thinnest part of the cylinder wall because they are cut directly over the center of the chambers. Which is already the thinnest part to start with.

Five-shot revolvers are stronger because the locking bolt notches are located between the chambers in the thicker web sections.

Correct. This is the same reason why 7 shot 686 cylinders are stronger than the 6 shot models.

But not all 6 shooters are created equal. Though I am a S&W guy overall, I'll give Ruger credit where it is due: The Six Series guns (Security/Police Service/Speed) and probably the GP100s as well have their cylinder stop offset to the right side in the bottom of the frame. This allows the stop notch in the cylinder to be slightly offset from the thinnest (and concequently the weakest) part of the chamber .

For those of you with both 6 shot K frames and 6 shot Rugers, check them out for yourselves.

---

As for what happened to my gun, as there was only one chamber with a problem and the rest of the gun is in excellent mechanical shape, my gut tells me that this was a handloading error on the part of the previous owner.

 

[dunnington]

hello,
this may be a stupid question, sorry if I am a noob hijacking the thread, but I am wondering if this can happen, is it safe to shot a 45/70 cartridge out of my 450 marlin bfr? I have never done it, but wondered if I could.

 

[kanook]

450 Marlin uses a 457

45/70 Gov uses a 458

While it may fit, you will probably get split cases and some other problems.

Only shoot what is marked on the firearm.

When in dought, contact the manufacture. If you encounter problems it's on the manufactures hands, not some person that said you could from the internet.

 

[Jonah71]

Why should Smith & Wesson, or any other manufacturer for that mater, fix a gun "for free" when what's wrong was caused by something beyond they're control, or in this case someone who fired an overloaded cartridge in it?

Stupid is a condition that should never be rewarded by "free."

LOL....Thanks. You just made my day. And I needed a laugh after seeing the posted pic of the Polymer revolver on another thread!

 

[Old Fuff]

Personally I approve of the use of massive overloads in any polymer revolver...

 

[rcmodel]

is it safe to shot a 45/70 cartridge out of my 450 marlin bfr?

NO.
The wide belted case of the .450 marlin chamber would leave a 45-70 case totally unsupported at the casehead.

While low pressure trap-door loads would probably not cause a major problem other then bulged cases, full power "Marlin" type loads most likely would.

rc

 

[rklessdriver]

jad0110-

I'm glad to see it never fully ruptured and you never got hurt.

I'm also pleased to see that you were able to find a good smith and get it fixed. Matt has done a good job (on 2 of my revolvers) for me as well.
Will

 

[Jim K]

That is a weakness of the S&W revolvers, especially the large caliber ones, and one of the reasons S&W preferred not to chamber for .45 cartridges, when the steel in that notch is literally paper-thin. Bulging like that doesn't happen often and it does take a load giving excessive pressure, but it does happen.

That condition almost never occurred with Colt DA revolvers because the stop notch is offset, but it did happen quite often with the SAA, and was one of the main problems when smokeless powder loads were fired in the old iron cylinder guns. It also never happens with five shot revolvers, again because the notch is offset.

Jim

 

[jad0110]

I'm also pleased to see that you were able to find a good smith and get it fixed. Matt has done a good job (on 2 of my revolvers) for me as well.

I highly recommend Matt Almeda (Suffolk VA). He is a super friendly guy, and he clearly loves what he does. And he is a THR member; he doesn't post often, but he does post under his real name. Not only did he fix my Model 15, he turned the barrel inward on my Model 13 to close up the B/C gap (it was running .012-.013", now it is running .006-.007"). He fixed BOTH guns and shipped them back to me (I dropped them off in person) for $200!!! Amazing!

---

Thing that suprises me most is that this happened on a .38 Special. But you know, in a way I suppose .38 K Frames may well be more susceptible to this sort of thing than Magnum K Frames. As others pointed out, many a moron has probably thought it'd be a great idea to hotrod a .38 Special case to .357 Mag performance levels, not taking into consideration the stouter heat treatment on the true .357 guns. Buldged or blown chambers being just a trigger pull or two away.

Expanded chambers are rare, but they are floating around out there. Most folks, including dealers, don't know to check for this sort of thing. Matt Almeda returned my damaged cylinder at my request, as a teaching tool. In fact, a local gunsmith that I am on good terms with has never seen a buldged/expanded chamber, so he'll get to see what one looks like shortly.