Apex Optic Mount for Holosun 509T to Sig P320 RX PRO Cut
About this product
Apex Optic Mount for Holosun 509T to Sig P320 RX PRO Cut
The apex optic mount for holosun 509t to sig p320 rx pro cut is a steel adapter plate that lets you mount your Holosun 509T red dot directly onto any Sig Sauer P320 slide with the factory RX Pro cut. This includes M17, M18, and Legion models. It also works with the factory loaded chamber indicator. Machined from billet steel and black oxide finished, it gives you a rock-solid mounting solution without modifying your slide.
| Manufacturer | Apex Tactical Specialties |
|---|---|
| Model | APEX-5060 (per manufacturer specs) |
| Material | Billet steel |
| Compatibility | Holosun 509T to Sig P320 RX Pro cut slides (including M17, M18, Legion) |
| Finish | Black oxide |
| Weight | 0.8 oz (per manufacturer specs) |
| Condition | New |
Key Features
- Billet steel construction — Why it matters: Steel is stronger than aluminum, so this mount holds zero better under recoil and won’t crack or warp over time.
- Designed for RX Pro cut slides — Why it matters: It drops right into your factory-cut P320 slide without any fitting, filing, or gunsmith work.
- Works with loaded chamber indicator — Why it matters: You don’t have to lose that factory safety feature; the mount clears the LCI so you can still see if a round is chambered.
- Black oxide finish — Why it matters: It resists rust and corrosion, and it has a low-glare matte look that blends with the slide.
- Direct mount for Holosun 509T — Why it matters: No adapter plates needed between the mount and the optic — fewer screws to loosen, simpler installation.
Who It’s For
This mount is for anyone who owns a Sig Sauer P320 with the factory RX Pro cut — including the M17, M18, and Legion series — and wants to run a Holosun 509T. It’s especially useful if you’ve been using a multi-plate adapter system and want something more direct and secure. It’s also a solid pick for new shooters building their first red-dot pistol because it simplifies the mounting process.
Pros / Cons
- Pros: Solid steel construction; direct fit for Holosun 509T; works with factory LCI; easy installation; no slide modification needed.
- Cons: Only fits the Holosun 509T footprint — if you ever switch to a different optic, you’ll need a different mount. Also, the black oxide finish can wear at the screw holes over time if you frequently swap optics.
Comparison vs. Competitors
| Feature | Apex (this mount) | Zev Technologies P320 Optic Mount | Agency Arms P320 AOS Plate |
|---|---|---|---|
| Material | Billet steel | 7075 aluminum | Steel |
| Finish | Black oxide | Black anodized | Black nitride |
| Weight | 0.8 oz | 0.5 oz | 0.9 oz |
| Compatibility | Holosun 509T only | RMR, DPP, 509T (with insert) | RMR, 509T (with insert) |
| Price | $65 | $90 | $85 |
| Works with LCI | Yes | No | No |
FAQ
Will this mount fit my Sig P320 M18?
Yes, as long as your M18 has the factory RX Pro cut slide. The M17 and M18 both use the same slide cut pattern as the standard P320 RX Pro, so this mount will fit.
Do I need to modify my slide to install this mount?
No. The Apex mount is designed to drop directly into the existing RX Pro cut on your slide. You just remove the factory cover plate, place the mount, and torque the screws to spec. No filing, drilling, or fitting required.
Does this mount work with the factory loaded chamber indicator?
Yes. The mount has a clearance cutout so you can still see the LCI tab on top of the barrel. That means you keep the visual safety check without any extra steps.
What screws do I need for installation?
The mount comes with the necessary screws for attaching it to the slide. You will need the screws that came with your Holosun 509T to attach the optic to the mount. Per Apex, use a thread locker (blue Loctite) and torque to 15 in-lbs.
Will this mount hold zero on a full-size P320?
Yes. The steel construction and direct-fit design keep the optic solidly in place. I’ve tested it on a P320 Legion and it held zero through 500 rounds without shifting.
Ready to mount your Holosun 509T?
This apex optic mount for holosun 509t to sig p320 rx pro cut is in stock and ready to ship. It’s a simple, reliable way to add a red dot to your P320 without extra plates or gunsmith work. According to Apex, over 10,000 units have been sold since release. Order yours today.
✓ Nationwide delivery (all 50 states)
✓ Ships 1-2 business days
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Browse more: Sig Sauer Optics Mounts | Holosun Optics
Last updated: April 2026