Quick question for you all, why is everyone recommending that I use 158 gr bullets in my Model 19. Is there an issues with using 125 gr bullets?

In .357, yes.
In .38 spl ammo, no.

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Science plus Art

Pulled this from another forum. Explanation is above my pay grade, but sums up what I've read.

The 125 grain bullets driven to maximum velocities used large charges of relatively slow-burning powders. Handloaders know the powder types as WW296 and H-110, among others. The combination of slow ball-type powders and the short bearing surface of the 125 bullets allows prolonged gas cutting of the forcing cone and top strap area, accelerating erosion and wear.

Borescope studies of rifle, machine gun, and auto cannon chamber throats shows a lizzard-skin-like texture due to this gas cutting damage, called "brinelling". The results of brinelling are fine microcracks that weaken the surface of the steel, and further promote erosion. In machine guns and auto cannons, barrel life is measured in terms of "useable accuracy", and round counts that determine this are based on group sizes at engagement ranges.

In the K-frame magnums, the forcing cone dimensions combined with the barrel shank dimensions results in a relatively thin shank at the 6 o'clock position, where a machine cut is made to clear the crane. This is usually where the forcing cone cracks. The L and N frames use much beefier barrel shanks and do not have this cut. S&W intended the K frame magnums to be "carried much and fired seldom" service arms, designed to fire .38 Specials indefinitely, with light to moderate use of .357 Magnums. You notice that S&W has discontinued production of K frame .357 magnums, no doubt due to product liability issues and a couple generations of K frame magnum experience.

This is how I understand it.

The issue is with full-power 125gr (and lighter) .357 Magnum loads. The combination of velocity and short bullet length allows more of the hot gases to hit the forcing cone than other loads. The bullet crosses the cylinder gap before the chamber pressure drops. Combine that with the thin forcing cone on K-frames and you end up with accelerated wear.

In heavier bullets, or in reduced-power loads, the bullet has more time in the cylinder gap, allowing the pressure to drop and reduce the amount of hot gases hitting the forcing cone and top strap. The longer time in the cylinder gap means the bullet acts as a partial seal.

FWIW, my favorite load to shoot when I had a 3" 65 was WWB 110gr SJHP, which was not a full-power load with a velocity somewhere around 1250fps, IIRC.

With the 125 gr bullets they were using up to 21 grs of W296/H110 . That same amount of powder is considered a max magnum load for the std bullet weight in 41 magnum , using the much heavier N-frame .
The K-frame , is just not that stout . Over time they loosened up .
The K-frame 357 was specifically designed for a minimum of 158 gr bullet , or heavier . It has a longer cylinder than the N-frame 357's to handle loading the Elmer Keith 173 gr swc in a 357 magnum case .
In the past I have shot a lot of 180 gr RNFP cast bullets over a max load of W296 ( about 13.0 grs ) in a 4" model 19 . Now days I have came to feel that the K frame 357 doesn't have to prove anything to me . I have backed off to just a real nice mid range 357 load . I consider the K-frame S&W 357's the perfect gun for the size , the balance , ease of handling and the power it delivers .

Thank you to all, this is what I wanted to find out. Now that I have some good info I will stick with mainly 38 sp to practice with and continue to use my 158 gr JSP for HD.

thanks for all the good info guys....

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be safe,enjoylife,journey well

This issue has little to do with the use of H110/W296 in handloads utilizing bullets weighing less than 140 grains. It has to do with the intended use of the gun envisioned by Smith & Wesson when designed, the popularity of the gun in the LE market along with the surge in popularity of the then new SuperVel type light HP bullet ultra high velocity ammo.

The design concept for the Model 19/66 was to build a medium frame LE duty .357 magnum revolver with target options which would utilize .38 Special ammo for practice and magnum ammo for qualification and duty carry. Their design was fine for this type of application but then the light bullet high velocity revolution happened and widespread problem began to appear. Smith & Wesson issued the recommendation not to use full power ammunition with bullets lighter than 140 grains as a response to the issues. It was reaction to the issues experienced by LE agencies equipped with S&W k-frame .357 magnum revolvers which at the time dominated that market. Obviously, these revolvers were loaded with factory ammo and not reloads.

Gas cutting of the top strap isn't a problem but forcing cone erosion & cracking is the issue along with fracturing of the frame's barrel mounting boss. To this day it is not unusual to find original k-frame .357 revolvers which exhibit eroded or cracked forcing cones and cracked frames in the used gun marketplace and no factory new replacement barrels exist.

Bruce

I wrestled with this question when I first acquired my model 65. Why... the manufacturer recommended it, that's why for me.

I think it's like goldie locks, not too hot not too cold, just right.

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Back to back World War Champs.

Using the Lee reloading manual on the starting side with a 125 jacketed bullet using 2400 or 4227 in my 19-3 at 50 yards on the bench is a+.

With all the new and improved "Modern Ammo" out there..........

You might take a look at the Barnes XPB 140gr for SD options.
Less chance of over penetrating vs the 158gr jacket.

The above post saying the H110 / W296 in light weight bullets was not the issue is "BS " . It has everything to do with the problems the K frames encountered .
The model 19/66 were NOT intended for only limited 357 magnum use . Bill Jordan who became the assistant Chief Inspector for the border patrol went to S&W and asked them to develop a lighter weight 357 than the N frames of the time . He did NOT ask for something to only shoot limited 357 magnum loads in . It is NOT common practice to find them for sale today with cracked forcing cones . There was actually only a very limited number of that occurrence and it was mostly in the -5's , for some reason .
And yes the PD's were still hand loading their ammo back then . The requirement for factory only didn't come along till later .
I'm tired of people posting **** that is not true about the K-frames .

I've personally only seen two split forcing cones in forty years both 19's. The "fix" for this is why S&W brought out the L frame, arguably the best S&W platform for the .357 Magnum cartridge. Don't tell my 28's I said that!

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Stay safe people!

I've gone to 130 grain Aguila's for my target shooting in all my K frames.

jpg images

Plus they look cool.

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Mike
S&WCA #3065