From what I read 158 Grain .357 Ammo is the way to go for the K Frame Combat Magnums to keep them from shaking loose.

How about 130 grain .38 Special ammo for the K Frame Model 66-8 .357 Combat Magnum? Has anyone had any issues with that?

Thanks to all!!

I shoot 130 gr .38's through my airweight all the time at the range. It is a very light load.
The hot 125 gr .357's are the loads to probably stay away from.

THE ISSUE WITH THE 125GR .357 AMMO APPEARS TO BE FLAME CUTTING OF THE TOP STRAP, RATHER THAN SHAKING THE GUN LOOSE. THE L FRAME 686 IS STRONGER THAN THE K FRAME 66. 130GR .38 SPL. LOADS ARE FINE FOR SHOOTING OUT OF YOUR MODEL 66. THEY ARE EASY ON BOTH YOU AND YOUR REVOLVER…..

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

Thank You One Eye Joe!!! You guys are teaching me a ton. I'll be keeping my .357 loads to the 158 grains as a lot of other members have suggested that grain and said if I stick to it that my 66 would probably outlast me
Thanks again!!

Keep in mind, there were no issues of flame-cutting caused by .38 Special ammunition, only light bullets out of .357s. I personally believe this happened waaaay less than you would be led to believe reading things from the internet.

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Because of the metric system?

Right on Pete! I have read it would take a lot of the light bullets to jack up the K frame as I heard the top strap could be flame cut or the cylinder shaken loose and being my first revolver I'm Uber paranoid about screwing it up. But all of you guys in the forum share great information!! Thanks again!!

The issue with high intensity light bullet loads, 110 and 125 grain, in the K-frame .357 revolvers was erosion of the forcing cone. This eventually leads to cracking of the barrel shank leaving the barrel un-serviceable. It has nothing to do with gas-cutting of the top strap, which will occur in any revolver to different degrees, and is not an issue as it tends to be self-limiting. It will stop before the strength of the revolver is compromised.

The biggest problem once a barrel crack develops is continued shooting will cause expansion of the barrel shank and damage to the frame from this source. When K-Magnum barrels were still available it was a simple matter of returning the gun too be re-barrelled, or purchase of a new barrel so your local gunsmith could change it. The supply of barrels has pretty well dried up so once you develop a barrel crack you own an expensive paper weight!

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Gunsmithing since 1961

That's what sold me on the 686 L-Frame. Smith and Wesson says it's built for continuous Magnum usage. I figured I'd have to mess up pretty bad to hurt it.

You know, I think a lot of this applied to older Model 66s, like the classic 66-2. I am pretty sure a modern 66 can handle any and all factory .357 without worry. What's more, should there be a failure - which I cannot imagine with factory ammo - it could be replaced. Not the case with a 66-2, hence the extra caution shooting hot loads with these older .357 magnum revolvers. But, modern - let 'er rip.

The only issue with .357 mag ammo in the K frame models is the cracking of the forcing cone where it is undercut from shooting full powered 125gr cartridges. This article shows examples of the damage and discussion of the problem: Use of Magnum Loads in S&W Model 19 and Other K-Frame Magnums Cracking the forcing cone ruins accuracy and damages the gun beyond repair as S&W no longer manufactures replacement barrels for the K frame .357 mag models.

All .357 mag revolvers will flame cut the back strap if many heavy loads using slow powders like H110/W296, 2400, etc. are used. Its cause by the large amount of hot gasses generated by slow powders escaping between the forcing cone and the cylinder producing the same results as an acetylene torch would. Flame cutting is visually unattractive but doesn't prevent the gun from being shot and is usually self limiting in the depth of the cut, never getting deep enough to cut through the frame or weaken it enough to render the gun unusable.

You can shoot any .38 spl load in your K frame .357 mags from standard to +P+ loads as none of them will reach .357 mag pressures so shoot all you want. Just be more diligent in cleaning the cylinders of power residue after shooting .38 spl.

Practice with 140 to 158 gr Magnums and limit your use of 125gr or lighter. I carry 125gr JHP full power loads in my .357 mag 19 and 66 for defense, just don't shoot many at paper.

I am a big fan of the older model 66 and 19's. My first handgun to shoot was a department issued model 19. We shot .38 +P for duty and that is all I have ever shot. I purchased a 2 1/2 model 66 for off duty and I still have it with .38 +P.

BUT, that being said, I watched a Jerry Miculek video on Youtube recently. It is pretty long but at about 14:50 he talks about the new model 66.

I think what SJshooter had to say is the case with the current model 66's based on what is in the vid. But you can decide that one for yourself.

https://www.youtube.com/watch?v=1cbV...-ts=1421914688

There are at least two 130 gr .38 Special loads available, the more common standard pressure FMJ from a bunch of different makers and the PDX-1 defense load from Winchester. Neither will overstress your K frame .357.

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Alan
SWCA LM 2023, SWHF 220

As the Model 66 is a .357, there will be no issues with ANY 38 Special ammo.

Wow!! From the videos to the articles I can't even begin to express my gratitude to you all!!!! I see that you all enjoy and care for your firearms as much as I do, and as I progress I hope to be able to share the knowledge I learn along the way!!

If you take up reloading you can load some really mild plinking loads that will further save wear and tear on you and your gun.

I've shot so much .38 Special 130gr fmj ammo out of my CS-1 686 that the rifling has worn away noticeably forward of the forcing cone. Many thousands of rounds to do it, 99.99% double action and generally at "warp speed". Still shoots well and hasn't lost any practical accuracy. The best thing is that no sight changes needed for 125gr .357 loads, in either this revolver or the 4" SS Python (which hasn't been as a "winning" gun in various matches, but has been a good supplemental carry piece.)

Main advantage to the 130gr fmj .38 loads for me has been ease and speed of reloads. Otherwise, for high volume shooting I like lead projectiles, HiTek coated especially anymore. That's what the various K frames usually eat.

From what I understand it is only full power Magnum 125s that cause the most damage. Even medium Magnum 110s and 125s seem to be rather tame. That being said, I hate the 130 grains FMJ .38 due the fact the seem very anemic, never hit right, and I always have light primer strikes with them. Give me 158s any day for plinking.

I've loaded some really hot handloads using all of those powders but I've never run any hot enough to flame cut the back strap. That's some REALLY hot handloads to flame cut that far back. A guy shooting those loads should wear fire protective gloves.

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183rd FBINA