When I first looked into buying a Model 19 I read a lot of posts in other areas of the internet as well as on here (I believe) that encouraged me to not use anything less than 158 Grain in the Model 19 due to the risk of cracking the forcing cone at the 6 o clock position.

I've only purchased both .38 special and .357 ammo in 158 grain or higher since then. I've only shot 158 grain .38's and .357 in the model 19 and I've shot those and higher grain loads in the Model 27. Is this something that I should consider as a risk for my model 27 as well?

There's often ammo especially at the moment available in lighter grains that peak my interest. Especially due to me using this ammo strictly for target shooting (steel mostly).

Is there a grain I should avoid for the model 27 or is anything fair game with that gun? Does it make a difference if it's .38 or .357 at a lighter grain? FMJ or SWC etc?

Should I stick to only using 158 Grain in the model 19?

Concern about shooting 357 magnums with bullets lighter than 140 grains applies to K frames. Feel free to shoot whatever .38 or .357 round you want out of an L or N frame (27), they’re tanks.

__________________
213th FBINA

Does this mean that any .38 special ammo doesn't require 140 grains or heavier for my model 19 as well? Only magnum loads must be above 140?

The 140 grain rule applies just to a regular diet of .357 magnums. .38 or .38 +P are fine in a K frame. You can fire the lighter .357 magnums in a K frame, however you may want to do it sparingly.

__________________
213th FBINA

Loading 158 grain lead all day long in your Model 19 will not be a problem unless you then shoot some lighter magnum or +P loads. The extra power loads will crack the forcing cone on your gun. I know because I've had it happen more than once and had to replace the barrels.

I now keep loading 158 grain loads and have not had a problem since.

The issue is erosion and subsequent cracks forming in the thin, flat spot at the bottom of the forcing cone in the K-frame S&W 357 Magnum revolvers. This is due to the huge charge of slow burning ball powder that is necessary to drive the light weight bullets at blistering velocities. Light weight bullets are fine in reduced loads, like the 357 Short Barrel ammo now made by many companies.

If you must use full power 357 Magnum ammo in a K-frame, then stick to 158 grain loads. If you love those nuclear flame throwing full power light weight bullet loads, then use them in a L- or N-frame S&W, the barrel extension in those revolvers have a larger diameter and are not likely to crack.

__________________
VCDL, GOA, NRA

I experiment with different handloads occasionally, but generally all I shoot in my Colt and S&W .38 and .357 revolvers is a 158 grain cast SWC. I've never found a lighter bullet that would provide the consistent accuracy that this bullet does.

However, I'd try a variety of factory offerings and /or handloads, even in various weights if you prefer, before making a decision on what's best for your gun. Perhaps the light bullets remain popular, but I can't imagine what real advantage they would have over heavier bullets of good design.

This topic has been discussed many times, so I'd suggest doing a search.

It's not a rule, but more of a suggested guideline.

The potential problem is with full-power lightweight bullets in .357 Magnum fired in older K-frames. You can shoot them, but it's generally recommended not to use a steady diet of them, for reasons that've already been stated. I believe the currently manufactured K-frames have a redesigned forcing cone that should at least mitigate, if not eliminate, the problem.

One of my favorite loads to shoot when I had a 3" 65 was WWB 110gr SJHP. Velocity is rated at 1295fps, which puts it in 9mm +P/+P+ ballistics, so not full-power. Low recoil, but made an impressive fireball. There are also a number of mid-range .357 Magnum self defense loads in 125-135gr bullet weights that would be perfectly acceptable in a K-frame.

Your N-frame should be able to handle them no problem.

If you hurt an M27, you've done something extremely impressive. And it won't be from using light weight bullets.

Beyond what other posters have mentioned, there are a few non wear issues where you might like medium to heavy weight bullets in 38 and 357. Lighter powder charges for the same muzzle energy, better terminal performance, better longer range performance, perhaps better accuracy in a particular gun.

Take a good long look at factory listings, tests, handloads for 38 Special, +p, 38-44, and 357 Magnum. Don't be surprised if you get the most performance out of these cartridges with heavier bullets, and the least from the lightest bullets. Nature of the internal ballistics of these cartridges.

Back in the day, S&W designed the M-19 ( K frame ) for a diet of 38 special with a full load 110 or 125 JHP for SD carry that would not be shot in high numbers.

Even today the 125 gr .357 is made to do 1450 fps but they have backed the lighter 110 JHP down to 1295 fps, which is a good thing, for the old K frames.

The L frame or larger frames are designed for ALL of today's .357 ammo, for as long as you can hold up with the recoil of these loads.

Have fun.

I'd sure like to understand this better because to me, erosion is erosion. Unless the forcing cone metallurgy is different between the frame sizes, both forcing cone internals should experience the same amount of erosion.

That tells me that the greater wall thickness is doing more than just allowing for more internal erosion before reaching the point where cracking can occur. The extra thickness must somehow be preventing erosion by limiting or changing the shape or nature of the burn/blast from the hyper ammo.

Can anybody help me understand this better? None of my K-Frames (even the ones I've bought well-used) have the forcing cone issue so I'm a little bit at a loss here.

It is my understanding that the weight of the bullet is not the problem. The problem is created by the fact that most people push the lighter bullet at a much higher velocity (because they can). If you shoot lighter weight bullets at relatively modest velocities I imagine that it would not be a problem at all. (Most of the ammo I shoot I make myself. I no longer enjoy shooting Rhino Rollers so I don't load them that way.)

My understanding is that the problem isn't necessarily the erosion itself, but that in a K-frame that erosion can lead to a cracked forcing cone. It'll still cause some erosion in a N-frame, but won't (shouldn't?) lead to the forcing cone cracking.

OK, so you've got a 19-4 with an unknown history. It probably has some erosion. With a strong light and a magnifying glass, a teeny tiny start of a crack is observed on the bottom of the forcing cone.

What to do? Shoot it with only target 158's? Not shoot at all?

(not even sure about the "crack". More of a "line". Certainly not separated yet)

One point: The Combat Magnum was introduced in the mid-50s. All commonly available .357 Magnum factory ammunition were 150-158 gr. loadings at that time. The use of lighter JHP bullets came much later (the so-called Super Vel revolution).

When the 110/125 JHP bullets are loaded with a full case of H110 or any other high temp, long burning powder, in the high fps magnum loads, there is excessive heat that burns for a longer time limit than a medium or fast powder, which in time can erode the top strap of some revolvers, if a lot of these rounds are short in the weapon.

It does not always happen but it can and has, so it is mentioned, to let shooters know what can happen when shooting certain loads.

Any weapon can be worn out with continuous heavy pressure loads that over work it's parts and metals. It is up to the owner to use ammo that will fit his needs and how long he wants to shoot the weapon.

I have seen a comp rifle barrel shot out in just one year, with a busy schedule........ though a hand gun should last six years if not over worked, with heavy use.

A lot longer with just target loads.