120gr only 357mag?

[daven59]

I purchased a S&W 340 snub nose 357mag and it warns you not to shoot 357 ammo with less than 120 grain bullets. Can anyone tell me what the reason for this is? Thanks

[SAFireman]

To prevent cylinder face erosion....the titanium cylinder can be damaged by the hot gasses being forced out with lighter bullets.

[BigBill]

I found out the sweet spot for the 357mag caliber with the 6" barrel is the speer 140gr JHP's in my reloads. Its been pin point accurate out at 100yds. I'm not sure about the shorter barrels accuracy. If i remember correctly i had the 125gr JHP's loaded to around 1500fps. Just some food for thought.

[murphydog]

I believe the reason is that lighter bullets will pull themselves out of the case crimp with recoil, which with full .357s in the 340 would be...interesting.

[jglsprings]

I think murphydog is correct. But, I haven't seen 110 grain 357 ammo for sale in a long time.

[daven59]

I asked the shop I got it(340 not the titanium cylinder model) from but I guess i didn't understand the answer. I have a box of old 110gn for my 686 6inch and guess it can handle that round? I'll just have to use the +p ammo and get the correct 357 mag ammo for it. thank you for your responses.

[Imshootin]

AMMUNITION WARNING
FOR Ti, Sc, PD Series
REVOLVERS

Before placing any of these reduced weight revolvers into
service, perform the following test to determine the suitability
of the ammunition you intend to use.

At a gun range or other suitable and safe location, prepare your
revolver for firing by fully loading its cylinder with the ammunition
to be tested. While pointing the firearm in a safe direction, fire all
but the last round. Remove the empty casings and the last
loaded round from the revolver’s cylinder.

Carefully inspect the loaded round to determine if its bullet
has started to unseat (move forward) from its casing.(Figure 2)
If it has, you should not use the tested ammunition in your
revolver. Choose another projectile weight or brand of
ammunition and repeat this test until you find one that
DOES NOT UNSEAT under these test conditions. When you
are finished, fully unload your revolver and secure it safely.


ALL SCANDIUM REVOLVERS FIRING MAGNUM AMMUNITION

WARNING: DO NOT USE MAGNUM® LOADINGS
WITH BULLET WEIGHTS OF LESS THAN 120 GR.
THIS WILL REDUCE THE POSSIBILITY OF
PREMATURE CYLINDER EROSION.

[Wheel Fan]

<120 grain is a pretty darn warm bullet