I hear a lot of talk about 125gr damaging revolvers (forcing cone erosion, flame cutting). I have always used 158gr for this reason but how many thousands of rounds would it take for those issues to actually become a problem on any a 686 L frame?

Well my understanding of the issue is that it’s only a big problem in the k-frame guns because the bottom side of the forcing cone is flat. The L-frames have a full diameter forcing cone and therefore last a lot longer. I can’t say how many rounds you could shoot through one before causing erosion problems but I think you would get tired of shooting before ruining the gun. At least that’s my opinion. I don’t shoot enough to worry about it lol.

The K frame barrels and sometimes the frame will crack at the bottom with enough high intensity loads, sometimes with enough target loads.

Erosion is worst with high pressure loads using a ball powder. This type of erosion makes longitudinal grooves around the forcing cone similar to water erosion of soil. It doesn't take long for it to start, but a barrel can get pretty bad before it has to be replaced. The L frame can get erosion, but won't crack.

I have often felt that todays factory stuff is not as hot as the loads of " yesterday " . Don't misunderstand me , the 125 gr loads are still pretty hot . The L frame will handle the 125 gr factory loads . It was built for the hotter loads in factory stuff . If you hand load using the older load data then , I would still limit them . Personally , iMO -- 140-158 gr is still the ideal 357 loads . Using current load data is more sensible . The Ball powders , W296-H110 are the hardest on a revolver . IMR 4227 is the easiest magnum powder on any hand gun . It looses a bit in velocity but is easier on the frame / forcing cone etc . Good Luck, Paul

WELCOME TO THE FORUM, Smithbug. I AM IN COMPLETE AGREEMENT WITH YOU. THE L FRAME M686 WAS DESIGNED TO OVERCOME THAT WEAKNESS IN THE K FRAME M66......

MY UNDERSTANDING IS THAT THE M686 CAN WITHSTAND AN UNLIMITED AMOUNT OF ANY FACTORY AMMO, WITHOUT INCURRING ANY DAMAGE. I CAN'T RECALL ANY POSTS ON OUR FORUM, REPORTING FLAME CUTTING OR EROSION PROBLEMS, ON A M686.....

I HAVE A SEVERAL 686s, THAT I EXPECT WILL OUTLAST ME AND MY CHILDREN........

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'Nam 1968-69.DAV,VFW,NRA Inst.

No problem in an L Frame.

Shoot away and enjoy.

Paul you are 100% correct. Some of the 'old loads' bordered on proof rounds. One reason was the testing equipment of the day, especially in measuring chamber pressures. If you were to compare loads printed in older reloading manuals say Speer #5 or #6 with what appears in the newest version, you'll see some of the old powders still in use today have much lower charges than they did way back when. Some guns have also had the maximum chamber pressure lowered as well. Although I have some old reloading manuals, I keep them for entertainment comparisons and NOT for reloading.

Back to the OP's question, you'll undoubtedly wear out other internal parts shooting full house 125 grain bullets in an L frame before the forcing cone needs to be replaced. Even then, replacement parts are still in plentiful supply either as the more recent MIM parts in newer guns or used/NOS parts if you want to retain originality in an older firearm.

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So many S&W's, so few funds!!

I’m not sure we’re the ballistics are on the new 357mg / 125gr that’s being offered today. The s&w 357 mg / 125gr jhp that was offered decades ago was 1597 FPS. We’re talking full house factory loads. My reloads weren’t too far off from the factory loads. My Python and police service six had no problem handling these loads. I had fun in my twenties with hot loads. Now I’m older and wiser plus shoot more for accuracy rather than looking at the flames �� on both sides of the cylinder and flames �� out the muzzle. I searched for the ultimate load in accuracy and tested a whole bunch of different bullet weights and powders. My most accurate load in my 357 magnum Python with a 6” barrel turned out to be the 140gr JHP using the 2400 powder with a small pistol magnum primer.

I have a 686 no dash that I carried as a duty gun in the 80's. Shot PPC and shoot IDPA with it. Tens upon 10's of thousands of rounds many were magnums.

S&W engineered the L-frames to withstand a lifetime of Magnum shooting...including the then very popular 125grSJHP.

your 686 will handle decades of 125gr magnum loads

The K-frames were designed for 38 special, I avoid 125gr magnums in those.

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NRA Life
USPSA/IPSC

Don't confuse cone wall thickness (strength) with resistance to erosion.
The L-Frame was designed to resist the CRACKING at the bottom of the cone in K-Frames, NOT to resist erosion from gas cutting.

The L-Frame's cone is just as vulnerable to erosion every bit as much with hotter 125s as the K-Frame was (and still is in the newer Ks).

Erosion is more a function of bullet configuration than cone thickness.
Cracking is a different matter.
Denis

i am in agreement with this statement based on my 586 no dash with a conservative round count of 25 000 rounds through it. Most are .38 spl lswc`s but at least 3-4 thousand 125gr XTP`s. This is over a 29 year time period. There is considerable FC erosion. It probably is limited to where it is now. It has no effect that I can point to to suggest it is a problem. It remains extremely accurate and functions as it should.
Jim

No common combination of any load will damage an L frame. It's specifically made to shoot .357 magnum and any .357 magnum cartridge within pressure limits will not damage the gun in any way.

K frames had a flat on the forcing cone that was vulnerable to certain combinations. The L frame doesn't have that flaw.

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"He was kinda funny lookin'"

Phooey on new ammo. You can get 'boutique' ammo that is fully loaded or I can reload .357 cartridges to max and it won't hurt it. And with any bullet. I don't shoot full loads exclusively at all, but neither do I avoid them.

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"He was kinda funny lookin'"

The flat weakness on the old K-Frames had nothing to do with erosion.
Erosion is a factor of high pressure gas cutting with lighter-weight jacketed bullets, and there's nothing about the L-Frame's barrel/cone that changes that vulnerability.

This erosion also has occurred in Ruger GPs, and it has ZERO to do with the old flat bottom section of the cone, or the lack of one.

The old flat was prone to cracking with repeated use of magnum loads, because the old K-Frame was never designed or intended for REPEATED heavy use of full-bore magnum rounds, and eventually the impacts could crack that thin section.
Denis

I saw a report from a person I know to be credible (either here or another forum to which we belong) regarding an N frame that had real erosion. It can happen - but no telling how many thousands of hot rounds that took - more than most of us could afford financially or physically, and certainly not something about which I would worry. I am sure that the L frame has some threshold at which it would show real wear, and maybe even need some serious work. I am also sure that the amount of shooting required is still well beyond the financial and physical threshold of almost everyone.

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NHI, 10-8.

I'd rather have erosion, at least the forcing cone can be turned down re-cut, and the barrel re-fitted. With a crack you'd be looking at a new barrel as well as re-fitting. I like my L frames.

Back in the 1980's & 1990's I'd buy 125gr SJHP in 1000 bulk along with 8lb jugs of H110/win296 magnum powder. Loaded on two DILLON machines.

My 586 and 686's didn't mind at all.

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NRA Life
USPSA/IPSC

Neither does the new 66-8.

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Waiting for the break of day

That was previously mentioned & again- it has zero bearing on EROSION.
Denis

The 125 gr. .357 is what the L frames were made for! A heavier top strap to deter flame cutting.
A larger diameter cylinder to provide for handling more pressure.
Tighter cylinder gap to help eliminate flame cutting. A full barrel underlug to reduce recoil.

All while using existing K frame grips!

Only shoulda' was venting of top strap!

Then it wudda been a S&W's version of the Python!

I was around when the L-Frame was introduced & had one of the first blued 586s out.
I know what the theory was behind the model.
I know what it was built for, and it wasn't built for 125-grainers.

If you persist in saying that the L-Frame was built specifically to reduce or eliminate FORCING CONE EROSION, please tell me exactly how the design does that.

And while you're at it, what in the L-Frame makes it stand up to specifically 125s, as opposed to 158s & 180s in general?

You can get flame cutting in the topstrap from other bullet weights.
The cylinder strength on K-Frame Magnums was not a problem in handling Magnum pressures.

The cylinder gap in L-Frames is every bit as variable as any other frame size S&W builds for .357 Mag rounds & has no relationship to being maximized for 125-grain .357 Mag ammo.

The heavier topstrap was more to resist stretching across all ammo weights than to reduce flame cutting in 125s.


The L was designed to address frame stretch, timing, and cone cracking, which it does.
The underlug was marketing, as a competitor to the Python.
Denis

The main point to remember here is; the L frame was the first platform specifically designed for the .357 magnum cartridge. The only problem that ever arose, that I'm aware of, was from the use of some brands of ammunition with soft primers that caused the back flow issue with the hammer nose bushing. I never had the problem with my gun, but Smith was quick to resolve the issue and will still modify all older guns to this day. There, I said it!

Flame cutting of the strap can happen to any magnum revolver with certain combinations of powders and bullets. It's accepted that flame cutting is self limiting, i.e. the damaged caused will not progress to the point that the strength of the gun will be compromised.

Now throat erosion in an L frame I haven't even thought about. I very rarely use any bullet less than 140 grains in my 686. So I guess I'm out of the throat erosion debate.

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"He was kinda funny lookin'"

It's an issue with the fractionally earlier time frame in which lighter weight bullets overcome crimp and neck tension upon firing to transition into the forcing cone that permits the flame and gases to beat on the barrel entrance. It's an issue for the K frame guns largely over the course of firing several hundreds, into thousands of rounds of full house light weight bullet ammunition. Sticking with properly assembled heavier weight (140 gr. and above) will drastically reduce such wear.

Exact same POTENTIAL erosion issue with any .357 model or brand, if the wrong combination of bullet & powder is used long enough.

The presence or absence of a flat on the bottom of the cone has no affect or influence on gas erosion on the circumference of the cone, and thicker cone walls won't prevent gas erosion.
Denis

L frame 357 magnum? You're talking about the 686.

It was designed specifically for continuous long term use of full power 357 magnum loads. There is nothing short of doubling charging with H110 that will hurt that gun.

I just wanted to add that although many "purists" cry about the frame mounted firing pin on the newer revolvers as being untraditional, ugly or whatever. People fail to realize that the frame mounted firing pin increases revolver reliability of the gun. On the older models with the hammer mounted firing pin, on some +P and magnum loads depending on the brand, the firing pin would divot the primer to the point of causing it to deform enough that it would make contact with the recoil shield. causing the revolver to "jam".

Frame mounted firing pins allow for a more consistent strike, alleviating that issue with some guns thus increasing reliability.


Which brings me back to the split forcing cone issue on the older K frame magnums. There is a flat spot milled under the forcing cone on the older magnum revolvers that is there to allow clearance for the cylinder. They have been known to crack under some circumstances although I've personally haven't seen it. But apparently it was a issue enough for S&W to design the 686.

On my guns the primer always contacts the recoil shield on every shot. How does that make it jam?

Buffalo Bore offers a 125 grain JHC that it rates at 1600 fps out of a 4 inch barrel and 1700 fps out of a 6 inch barrel. Now that's HOT! I used to shoot that sort of thing with my 6-inch Colt King Cobra as a sort of cathartic therapy (selling that gun is one of my few firearm regrets). But I'll stick with 158 grains and up for my 4-inch m66-2. That sort of ammo and an m686 are a match made in heaven. Or was it recoil hell? One of those two anyway. Take your pick

There may be some truth to that, but I always thought S&W came out with the m686 mainly in response to market demand, i.e. due to the popularity of the Colt Python and King Cobra—to which it bears a certain resemblance.

It's good to remember that almost anything you "hear a lot of talk about" is doubtful at best, and often entirely false.

When it comes to 125 gr. ammo, it will do absolutely no harm to an L-frame revolver, and the number of K-frames that have been damaged by it is so small as to be statistically insignificant.

If "everybody says", or you hear "a guy at the gunshop told me", your first reaction should always be healthy skepticism.

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Pisgah

In the summer of 1980, fresh out of college and making good money for the first time in my life, I bought my first new gun, a S&W Model 19-4. I naively used data from an old Speer manual and 125 grain jacketed HP bullets. I shot those overloads exclusively.

The forcing cone cracked at about the 750 round count. S&W repaired the barrel under warranty, but it was my fault. Lesson learned.

So yes, the forcing cone on K frame barrels can crack.

I had a Python at the time when the L frames first came out, and was so disgusted at S&W's attempt to copy that barrel profile that I never could warm up enough to them to buy one. It still really turns me off.

So now if I want that hot .357 magnum shooting experience, it is from one of my N frame revolvers.

(Edited to add) One time I was at a gun range shooting my 6" Python when some clown with a big grin came over and asked, "Is that a Dan Wesson?" My temper being short as it was in those bygone days, he was lucky he didn't get shot! :-)

All I can add to the great information already given is, flame cutting on the top strap happens with all revolvers and is considered to be self-limiting.

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Always Stay Strong!

This is an interesting thread. I served a total of 32 years in law enforcement, most of which required a revolver for duty use. The last 12-15 years we were allowed auto pistols and I immediately changed over. The revolvers were required to be 38spl / 357 but we were issued 38spl and required to only carry and use 38spl on and off duty. Our range staff constantly tested ammunition in order to find the best available for our use. I was around when the 125gn rounds hit the market and immediately became the favorite of the gun magazines. My department never approved them in spite of the numerous articles in the gun press crediting the 125gn with the most one shot kills of any bullet at all. Our range staff also considered penetration through car windshields and other items of cover and never went to any bullet lighter than 140gn. I am not demeaning the capability of the 125gn. but we never used them. Then along came the stories of forcing cone erosion, frame cracking in K frame guns and other stories. I doubt that all of these stories are true, based on truth or are all that common. However, in my 38spl, give me a 148gn jacketed soft point and in my 357s give me 158gn jacketed soft point. When I shoot a feral hog I like to see the eyes cross when the bullet strikes. For thin skinned game give me the same jacketed rounds or lead rounds of the same weight. However good the 125gn round is stated to be, I see no need for it and all of the potential problems that can be linked to it. Give me 140gn bullets and up and I will never look back. Just my opinion.

Ball powder (296) and 125g JHP ate up the forcing cone on my first 586.

I'd say, switch to 2400 if you want to push those light bullets.

For me, I'll stick to 160g cast SWC, but that said, I still find 2400 to be premium in the 357. I'll save the 296 for the 44, 454 and 480.

If you shoot 50K rounds thru your 686 and wear out the barrel, just send it in for a new barrel.