The Smith & Wesson M&P340 J-Frame 1.875 in .357 Mag 5-Rd No Internal Lock is a lightweight scandium-framed revolver built for deep concealment and serious personal protection. Chambered in .357 Magnum and .38 Special, it packs five rounds of potent defensive ammunition into a compact package that disappears under a T-shirt. The enclosed hammer design prevents snagging on clothing during a rapid draw, and the XS Sights 24/7 tritium front sight ensures you can align your sights in low-light conditions. This model omits the internal lock, giving you a cleaner, more reliable trigger system for everyday carry.
Specifications
| Manufacturer | Smith & Wesson (per manufacturer specs) |
|---|---|
| Model | M&P340 |
| Material | Scandium alloy frame, stainless steel cylinder |
| Compatibility | .357 Magnum / .38 Special +P ammunition |
| Finish | Matte black |
| Weight | 14.5 oz unloaded (per manufacturer specs) |
| Condition | New |
Key Features
- Scandium Alloy Frame: Weighs only 14.5 ounces unloaded, making this revolver easy to carry all day without fatigue. The lightweight construction doesn’t compromise strength — it handles full-power .357 Magnum loads.
- Enclosed Hammer (Shrouded): Snag-free design means the hammer won’t catch on your shirt or holster during a defensive draw. This is critical when every split-second counts in a self-defense scenario.
- XS Sights 24/7 Tritium Front Sight: The bright tritium insert glows in total darkness, giving you a clear aiming reference without needing a flashlight. The integral U-notch rear sight keeps the profile low and snag-free.
- No Internal Lock: Eliminates the potential failure point of a lock mechanism, providing a smoother, more reliable trigger pull. Many concealed carriers prefer this configuration for its simplicity and dependability.
- .357 Magnum / .38 Special Compatibility: You can practice with affordable .38 Special ammo and load up with .357 Magnum for carry. The 1.875-inch barrel is optimized for defensive distances, typically under 10 yards.
Who It’s For
This revolver is built for the concealed carrier who prioritizes reliability over capacity. If you carry in a pocket holster, ankle rig, or IWB holster, the M&P340’s compact dimensions and lightweight frame make it an ideal backup or primary defensive tool. It’s also a strong choice for home defense, especially if you prefer the simplicity of a revolver over a semi-auto pistol. The no-internal-lock feature appeals to shooters who want a clean, uncluttered trigger system without extra mechanical parts.
Pros & Cons
- Pro: Extremely lightweight at 14.5 oz — one of the lightest .357 Magnum revolvers on the market.
- Pro: Enclosed hammer eliminates snagging during a draw.
- Pro: Tritium front sight works in all lighting conditions.
- Con: Recoil with full-power .357 Magnum loads is stout — practice with .38 Special to build proficiency before stepping up.
- Con: Five-round capacity may be limiting for some users compared to modern semi-auto pistols.
Comparison: M&P340 vs. Competitors
| Feature | Smith & Wesson M&P340 | Ruger LCR .357 | Colt King Cobra Carry |
|---|---|---|---|
| Weight (unloaded) | 14.5 oz | 17.1 oz | 25 oz |
| Frame Material | Scandium alloy | Polymer/aluminum | Stainless steel |
| Hammer Type | Enclosed (shrouded) | Enclosed (shrouded) | Exposed spur |
| Sights | XS tritium front, U-notch rear | Red ramp front, U-notch rear | White dot front, adjustable rear |
| Internal Lock | No | Yes (some models) | Yes |
| Price | $967.67 | $719 (approx.) | $999 (approx.) |
Frequently Asked Questions
Is this revolver suitable for pocket carry?
Yes. The M&P340’s 14.5-ounce weight and 1.875-inch barrel make it an excellent pocket carry option. Pair it with a quality pocket holster to keep the trigger covered and maintain a consistent draw stroke.
Can I shoot .38 Special +P ammo in this revolver?
Absolutely. The M&P340 is built to handle .38 Special +P and .357 Magnum loads. .38 Special +P offers a good balance of reduced recoil and effective terminal performance for self-defense.
Does the lack of an internal lock affect reliability?
No. The internal lock is an additional mechanical component that can potentially break or bind. Omitting it simplifies the trigger system and removes one potential failure point. Many experienced shooters prefer the no-lock configuration for its reliability.
What holsters work best with this revolver?
Look for holsters specifically designed for J-frame revolvers with an enclosed hammer. IWB, pocket, and ankle holsters from brands like DeSantis, Galco, or CrossBreed are popular choices. The snag-free profile fits most standard J-frame holsters.
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Last updated: April 2026
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