Friday, April 22, 2011

Flyweight fly-apart.

Saw some creepy-looking pictures of a S&W Model 329 Night Guard that suffered a catastrophic frame failure.

Note that this had bupkis to do with the ammunition being improperly loaded: This was not a "ka-BOOM". The cylinder and barrel are quite intact.

This was apparently with Remington's 180gr load, which is to the .44 what the high-velocity 125gr loads are to the .357 Magnum. It is a very high velocity projectile, in excess of 1600fps at the muzzle, which means it's probably hitting the forcing cone at over 1,000fps.

If I had to pull a guess out of a hat, the barrel was improperly torqued, putting the frame under stress, and it just fractured under the pounding. The failure mode is almost identical to the one suffered by Will's S&W PC625 (another alloy N-frame, which gave up the ghost firing comparatively tame 185gr .45ACP.)

Both my daily carry revolvers are alloy-framed guns with the two-piece barrel, and to give Smith their due, the failure rate is awfully low for the volume they sell, but this is bad PR.

33 comments:

Bubblehead Les. said...

Being serious for a change. What are you carrying, what loads do you have in them, and in light of these reports, do you trust them?

staghounds said...

Good thing revolvers never malfunction! ;)

Will Brown said...

I've been holding off on blogging a follow-up as I'm still :) awaiting it's arrival, but S&W customer service employees are quite professional in their handling of these (statistically) rare occurances and are/will-some-day-real-soon-now replace my 625 with a 325 Night Guard having the identical characteristics that originally made the 625 an attractive buy for me.

I asked and was told that the metallurgical report didn't specify an exact cause, but the over-torque thesis seemed consistent with what was discovered.

I think those of us who own and carry these alloy framed pistols ought to give serious consideration to deliberately firing relatively low-powered ammo as a general rule (that is, relative to a given gun's theoretical tolerance and design parameters). If you really want to shoot the maximun end of the tolerance range or do a lot of practice, buy a steel framed version of the same gun and reserve the fancier alloy frame gun for periodic carry duty only.

A gun's effectiveness as a defense weapon (particularly at the ranges typical of self-defense shootings) is very much a matter of bullet terminal performance, how well it transfers the available energy to the target. Select a bullet design that achieves the desired effect from a powder load that develops energy levels about mid-way up the tolerence scale of your gun and stick to shooting only that ammo and a lot of these incidents will be avoided in future I think.

That's my plan anyway.

armedandamphibious said...

Thanks for spreading this around Tam. I thought people should be aware of the remote possibility.

I'll stick with my stainless 629's.

Salamander

Boat Guy said...

Guess I'll stick to my "old-fashioned" N-frames... they're heavy, but what did the man say? "Carrying a gun is supposed to be 'comforting' not "comfortable'"

Mulliga said...

From what I read on the Errornets, S&W's quality control has slipped a bit in recent years - it's hard to keep things consistent when you're manufacturing eleventy different types of revolvers, pistols, and rifles.

The customer service is as good as ever, though - I sent in my trusty old 642 a month ago (it was getting loose after many thousands of rounds) and they sent me a brand new gun. Can't ask for much more than that.

Tasso said...

The mythology of the .44 Magnum continues, with someone who should know better. The 329 Night Guard would be lucky to get a 180 grain pill up to 1100 fps at the muzzle... 1600 is fantasy land.

The only thing a 329 is good for is nerve channel compression and night blindness.

Tam said...

Tirno,

The 180gr Remington is not a reduced velocity load. Remington claims in excess of 1600fps out of a vented 8" test barrel, and full-house 180gr loads regularly chrono 1500+ out of real guns (albeit in the more common 6"-8" lengths found in .44's.) (cf. the first thing I found on Google: http://www.m4carbine.net/showthread.php?t=72486 )

Given the rough "50fps per inch of barrel length" rule of thumb, it's not out of line to expect a velocity at the forcing cone of over 1,000fps.

Sincerely,
Someone Who Should Know Better :)

Tam said...

Les,

My two alloy-framed carry guns are the 432PD I use for pocket carry, which is usually loaded with Georgia Arms .32H&R Mag 100gr SJHP at a claimed 1000fps, and a .44 Special 296Ti, which is loaded with Federal 200gr LSWC-HP or CCI Blazer 200gr GDHP, both of which are moving at pretty leisurely speeds in the ~900fps neighborhood.

Terry said...

To be fair, the 1600 fps that Tam quoted is not out of a snubby. Her guesstimate that the bullet would hit the forcing cone at 1000fps is in line to what you just wrote.

In any case, if I had to have a lightweight big bore revolver, it would be in 44 Special or perhaps 45 ACP.

No Magnum in the scandium for me.

atlharp said...

Damn plastic guns.....oh wait... ;-)

Tasso said...

"This is a .44 Magnum Night Guard, the most powerful recoil in the world, and can blow my hand... clean off. I've got to ask myself one question: do I feel lucky? Well, do I, punk?"

Tam said...

Hey, at least the Night Guard has a steel cylinder. The Ti-cylinder 329PD is the absolutely sick one. I have no particular desire to shoot one of those again.

Hank said...

I can't visualize the bullet going from a rest state to over 1000 fps by the time it reaches the forcing cone.

I would envision some acceleration factor that drops off slightly between the initial point of the bullet sitting there, and when it exits the barrel.

I can see that perhaps the acceleration drops to a great degree as a function of the distance from the originsl resting point of the bullet, but to the degree you seem to be stating, the initial acceleration would be phenomenal and rapidly drop off to trivial in the space of an eighth of an inch or so.

Got acceleration & velocity graphs? Otherwise I can't see it.

Hank

Bubblehead Les. said...

Thank you Tam. Enjoy your Blogmeet this weekend!

Tam said...

Hank,

"Got acceleration & velocity graphs? Otherwise I can't see it."

I'm extrapolating from the fact that the 125gr .357 Magnum is doing ~1100fps @ the forcing cone with a roughly similar muzzle velocity.

Ed Foster said...

They've had a long standing recall out on the 329, but not the 329PD with the 2 piece barrel.

Serial numbers BVA0004 to BVA0210 and DEW0001 through DEW0099.

It's Monday Morning Quarterbacking, but that Scandium/Aluminum alloy always left me a bit squeamish on the subject of stress risers, and that isn't exactly a Ruger style frame radius above the barrel.

Rugers are pretty crude, but they cast in some big radii. Lots of flex in the corners.

Anybody hurt when it blew? We had two local cops shredded up at the S & W academy week before last when an M&P 15 vaporized it's upper reciever.

Anonymous said...

My 3" 629 throws a 320gr WFNGC 1160 fps on average, chronograph confirmed. It's pretty brutal recoil but not damaging. I prefer a 300gr @ 1100 or so though, for quicker follow up shots and easy extraction.

Given that, I think I'm justified in thinking a 180gr bullet would go a LOT faster than 1100 fps if I wanted it to.

- weambulance

Tasso said...

http://www.gunblast.com/SW-Nightguards.htm has a 329NG tested with the Remington 180 grain load in question, and clocked at 1383 fps at the muzzle. So I stand corrected.

Given the 329 Night Guard recall for frame problems, I think would still give it a pass.

TBeck said...

The 329PD isn't so bad if you cover the backstrap with a Pachmayr or a Hogue grip. I shoot mostly .44 Specials out of it but Speer's "Snubby" .44 Magnum load (200 gr GDHP @ 1,050 fps) is pretty controllable.

staghounds said...

"No one who fired it cared to shoot with it again."

Old NFO said...

I was wondering if this was an assembly issue, sounds like it from your comments/post. Thanks for the update

TBeck said...

I fired a cylinder of standard .44 magnums out of the 329PD once. My hand was numb when I was done.

The Raving Prophet said...

As much as I like the feel of the N frame, it's rather large and difficult to conceal, so an alloy frame isn't all that worthwhile in one (IMO). I even say this as a 327 TRR8 owner; the gun shoots great, feels wonderful, and the look is an abomination against all that is pure and right in revolvers (that's why I love it), but I can't say a 329 sounds like anything I'd ever consider.

Still, S&W needs to get a handle on this barrel torque issue. Methinks that if this is anything other than extremely rare, it might actually save money to go back to pinned barrels.

Gewehr98 said...

That whole barrel torque thing is gonna be an albatross around S&W's neck, methinks. My own 696 No-Dash has a prominent ring visible in the rifling at the barrel/frame juncture just ahead of the forcing cone. A discussion I started at the S&W forum revealed others with the same "feature". It's as if they gave it some extra "oomph" during assembly since they knew the barrels were no longer going to be pinned...

Firehand said...

Damn. The pics are downright scary, and this 'overtorquing' business makes me wish they'd go back to pinned barrels.

I once fired five rounds of .41 Mag through a Taurus Total Titanium Tracker, and swore I'd never shoot one again; I'm not much recoil-shy, but OW!

Ed Foster said...

Gewehr 98, it was a timing problem at the turning operation on the barrel shank, and a behind schedule foreman didn't want to get reamed for starting the run without a first piece setup being finished beforehand.

A buddy in assembly covered for him by allowing a bit more torque at fit-up. In the old days, the front of the frame would have been dressed down to allow proper torque, but the holding company now owning Smith wants minimal time lost to handwork. Don't ask me how I know.

Tam said...

Gewehr98,

"It's as if they gave it some extra "oomph" during assembly since they knew the barrels were no longer going to be pinned..."

While chiming in after Ed is pointless, since he knows more about this than you and I combined, I'll note that, all things being equal, the 2-piece barrel is much better than the 1-piece unpinned barrel in nearly every respect except aesthetics...

Gewehr98 said...

Yeah, I figured it was somebody trying their best to get the front sight to line up with the rear sight mo' better instead of spending a few seconds on the lathe the proper way. The gun shoots just fine, and many others have stated they've found the same condition, so thanks Ed and Tam for confirming my hunch. I've had my machinists submit first articles that were rushed in the name of manufacturing expediency, too. As quality manager dude, I sent them back to their machines, though. Having customers return parts that shouldn't have left the doors ain't worth the savings in setup time, IMHO.

Mark B. said...

Ed, what are the chances that the barrel's forcing cone simply wasn't chamfered properly?

Have a 629-5 (8-3/8" barrel) that had precisely that problem new out of the box. Fired a cylinderfull, kicked like an S.O.B. -- far harder than it should've -- really hard extraction and split cases. My first thought was a/several loose chambers. Sent it back and S & W and they replaced the barrel. Shoots like a dream now.

'Berg

Ed Foster said...

Berg, was there any lead spitting or leading in the cone? If there's one thing Smith isn't noted for it's bad timing, but stuff happens anywhere. Just not as often at Smith as elsewhere.

Also, I doubt an undersized cone would increase recoil that much. It's primarily there to allow for misalignment, of which there is quite little in 629's, especially the later dash numbers, and the bullet is essentially a plastic at that point in it's travels.

Honestly, and I say this as a former engineer at both Colt's and S&W, they really do make the best damned revolvers in the world.

O.K., they tweak here and there, eliminating the odd screw or something whenever the latest owner (owner turnover being the real problem) wants justification for the continued existence of a design department, but the metallurgy (at least ferrous) and workmanship just get better and better.

The chief metallurgist there is the son of an absolutely amazing guy named Art Avadesian, a former teacher of mine, who got me into this screwy business. John is about as smart as his old man, and that's as smart as it gets.

And they've finally merged the best points of CNC and good manual work (if you don't mind the very expensive new automated polishing machine burning to the ground, but that was op error and a steep learning curve).

At Colt I was on the military side, but I'd talk shop with the commercial guys and was loaned to them for the .22 auto pistol (now a Beretta). I was impressed when I heard a senior Colt engineer on the revolver line say that he wished he could make his cylinders the way Smith did, but that management wouldn't let him spend the money.

Which was odd, as Colt made a good revolver, but with enourmously greater amounts of handwork than Smith. Penny wise and pound foolish, or maybe just not willing to buck the friggin' union.

Think of every horrible cliche about unions, double it, and that was the UAW at Colt's in the late 80's and early 90's. The bastards gutted that company, and it's never come close to recovering.

Which is ADD-type wandering or pre-senile dementia, forgive me. I suspect your observations about the cylinder were probably right, and the reason you got a new barrel was that they had to swap one in to maintain proper gap.

For reference, that's .002 to .006on a Smith, but you'll rarely see more than half the max, with essentially zero difference all the way around.

Hold your 629 up to the light and index the cylinder all the way around. I'll bet you don't see damn-all for variation, and I'll be suprised if you get a .004 shim in anywhere between barrel and cylinder.

Now consider how many things have to run right to get that kind of nice. There are people still at Smith who can screw up a wet dream when it comes to longarms(management, not engineering), and there are elements (also in management) that have what I think of as a skewed view of auto pistol design, but what they do 10,000 times a week on the revolver line is as close to perfection as anyone is likely to get, far more than 99 times out of 100.

Anonymous said...

My Ti-cylinder 329PD is at the factory right now getting a black steel cylinder installed.

Mark B. said...

Ed, don't want to completely jack this thread, but maybe I should've been more specific.

That particular gun is a 629 Classic, and I got the dope on the problem straight from S & W. When they found it out they went through the gun stem to stern. When I got it back I did more-or-less what you suggested (a long way from my first rodeo with N-frames, I'm a round-heeled whore for 'em), the gun is put together and though I've not yet had the opportunity to really wring it out, I suspect that I got back a gun that'll meet DX specifications for my trouble.

As you're familiar with the metallurgical side and know the Avadesians as well (and you're not the first I've heard say what you did about them), maybe you could explain or speculate on what went wrong on the cylinders of the original 629s which, if memory properly serves, also were introduced just subsequent to an ownership change.

'Berg