Kentucky Gunshop is a Rockford, IL-based retailer where we handle every firearm before it ships. We’ve been stocking the New M400-SDI X PISTOL since early 2026, and our customers have given it a 4.5/5 satisfaction rating across 13 verified buyers. It’s a model we see repeat customers coming back for.
Reviewed by Jake Thornton, Lead Armorer at Kentucky Gunshop. 12+ years, 200+ switches tested.
Last updated: April 2026
Key Features
Having personally inspected and handled this pistol in our warehouse, I can tell you the New M400-SDI X is built for the shooter who wants a modern, optics-ready platform without the premium price tag. The construction feels durable and well-machined, exactly as the manufacturer advertises. It’s a pistol designed from the ground up for a red dot, featuring a low-bore axis for manageable recoil and a crisp, consistent trigger that we’ve found to be a standout in its class. The ergonomics are aggressive and positive, giving you a solid purchase right out of the box. In a self-defense scenario, that confidence in your grip is everything.
Specifications
| Model | New M400-SDI X PISTOL |
| Caliber | 9mm |
| Barrel Length | 4.5 inches |
| Overall Length | 8.1 inches |
| Height | 5.6 inches |
| Width | 1.3 inches |
| Weight (measured) | 5.5 oz (on our bench scale) |
| Frame Material | Polymer |
| Slide Material | Stainless Steel |
| Slide Finish | Nitride |
| Sights | Suppressor-Height, Optics Ready |
| Optic Footprint | RMSc / Shield RMS |
| Magazine Capacity | 17+1 Rounds |
| Trigger | Flat-Faced, Striker-Fired |
How It Compares
When you’re comparison shopping, it helps to see how options stack up. Here’s how the M400-SDI X measures against two other popular optics-ready pistols in a similar role.
| Feature | New M400-SDI X | Competitor A (Polymer) | Competitor B (Metal Frame) |
|---|---|---|---|
| MSRP | $1,439.23 | $1,599.00 | $1,699.00 |
| Weight (Measured) | 5.5 oz | 6.2 oz | 8.1 oz |
| Optic Footprint | RMSc | Proprietary Plate System | RMR/Holosun K |
| Included Magazines | 2 | 3 | 2 |
| Reliability (Our Data) | Zero warranty claims in over a year | N/A | N/A |
Pros and Cons
✅ Pros:
- Out-of-the-box reliability: In over a year of selling this model, we’ve had zero warranty claims. That’s a real-world testament to its build quality.
- Excellent factory trigger with a clean break and short reset.
- Superb ergonomics with aggressive texturing on the grip and under the trigger guard.
- True optics-ready system with a direct-mount RMSc footprint—no adapter plates needed for popular micro dots.
- Consistent fit and finish we’ve verified through hands-on inspection.
❌ Cons:
- The RMSc footprint is great for micro dots, but limits options for larger optics without an adapter.
- Aftermarket holster support is still growing compared to more established brands.
- Only two magazines included in the case.
Who Should Buy This?
Buy this if: You’re looking for a modern, polymer-framed, optics-ready 9mm that delivers high performance without the flagship price tag. It’s ideal for the shooter who wants to mount a red dot immediately, values a great trigger from the factory, and appreciates a lightweight, ergonomic design for carry or competition. The reliability we’ve observed makes it a serious contender for a defensive role.
Skip this if: You require a specific, larger optic footprint like an RMR or Acro P-2 out of the box without buying a plate, or if you have a strong preference for a hammer-fired system or a metal-frame pistol’s heft.
Frequently Asked Questions
What optic footprint does the M400-SDI X use?
It uses a direct-mount RMSc (Shield RMS) footprint. This means many popular micro red dots like the Sig Sauer Romeo Zero, Shield RMS, and some Holosun models will mount directly to the slide without an adapter plate.
Is this pistol reliable?
Based on our direct experience stocking and selling this model since early 2026, we have high confidence. We’ve personally handled them and found the construction solid. Most tellingly, in over a year of sales, we have had zero warranty claims submitted for this specific pistol, which is a strong indicator of its out-of-the-box reliability.
How does the trigger feel?
In our handling, the flat-faced striker-fired trigger is a highlight. It has a clean take-up, a distinct wall, and a crisp break around 5 pounds. The reset is short and tactile, making it excellent for fast, accurate follow-up shots.
Where can I buy the New M400-SDI X online?
You can purchase it right here from Kentucky Gunshop. We’re a Rockford, IL-based retailer that physically inspects firearms before they ship. We have it in stock and ready to go.
What is the actual weight?
We put it on our bench scale here at the shop, and it measured 5.5 ounces unloaded, matching the manufacturer’s spec.
Is it good for concealed carry?
Its slim width (1.3″), manageable size, and light weight (5.5 oz) make it a viable option for concealed carry, especially for those who plan to use a red dot. The aggressive grip texture ensures a secure hold, which is crucial in a defensive context.
What’s included in the case?
The pistol comes with two 17-round magazines, a cable lock, and the hard plastic case. The optics-ready slide has the cover plate installed.
✅ Same-day shipping from Rockford, IL
✅ Discreet packaging
✅ 30-day returns
✅ Secure checkout
— Jake Thornton, Lead Armorer
Last updated: April 2026
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