About Arex
Arex is a firearms manufacturer based in Slovenia, mostly known for producing handguns and ammunition. It is owned by the Czech investment group RSBC which acquired it in 2017. Established in 1994, the company has catered to both the civilian and military sectors. They have a background in the tooling industry which provided them with a foundation in precision and quality. Arex Defense plays a significant role in Slovenia’s national defense and police sectors, and their pistols have also garnered attention in the international firearms community. The company continues to expand its presence in the international arms industry.
About Arex Delta M Gen II
The Arex Delta M is a semi-automatic pistol with a striker-fired, double-action trigger mechanism. It features a 102 mm barrel and a magazine capacity of 17 rounds (15 + 2). Designed with concealed carry in mind, its sleek design reduces the chance of snagging on clothing. This model includes a polymer frame, a Picatinny rail for attachments, and ambidextrous controls. It is available in the following calibers:
- 9×19
It comes with four backstraps of varying sizes and a customizable grip module. The pistol has metal sights and is rated for +P ammunition, though regular use may hasten wear and tear of the gun. It is not silencer-compatible. As far as the colour of the frame is concerned, there are three options:
- Black
- FDE (flat dark earth)
- Grey
This article examines the options for mounting red dot sights on the optic-ready Arex Delta M Gen II model. The handgun is also available in a non-optic ready version – the red dot mounting possibilities of that version are not covered in this article.
Differences between Arex Delta Gen I and Gen II
The Arex Delta Gen II maintains all the favorable features of its predecessor while introducing several enhancements. The Arex Delta Gen II comes in three size options: the M, maintaining the compact size of Gen I; the L, a full-size variant similar to the Glock 17; and the X, which combines a full-frame size with a compact slide. The frame comes in three colors: black, FDE (Flat Dark Earth), and grey. An upgraded grip module features a different texture with a smoother factory finish. The Picatinny rail on the bottom now includes three slots instead of one. Additionally, the Gen II boasts an enlarged, flared magwell, facilitating faster and more reliable reloading.
The properties of the optic-ready version of Arex Delta M Gen II
Arex Delta M Gen II has an optic cut that measures 48 mm in length and 23.5 mm in width.
According to our knowledge, no red dot can be mounted directly onto the optic cut (see the image below). An adapter plate is needed. If you know of any red dot sight that can be mounted directly on this pistol’s cut, please send an e-mail to [email protected]
Five adapter plates are included in the box. They are marked Type 1–5:
- Type 1 – Docter/Noblex mounting standard
- Type 2 – Trijicon RMR mounting standard
- Type 3 – Leupold DeltaPoint Pro mounting standard
- Type 4 – C-more mounting standard
- Type 5 – Shield RMS/SMS mounting standard
Type 1 adapter plate is designed for the Docter/Noblex mounting standard. The plate measures 48 mm in length and 25.4 mm in width. Red dot sights with Docter/Noblex mounting standard that have a mounting surface wider than 25.4 mm protrude over the edges of the plate (you can find the dimensions in the table below).
Red dot sights compatible with the adapter plate Type 1
Type 2 adapter plate is designed for the Trijicon RMR mounting standard. The plate measures 48 mm in length and 28 mm in width.
Red dot sights compatible with the adapter plate Type 2
Type 3 adapter plate is designed for the Leupold DeltaPoint Pro mounting standard. The plate measures 48 mm in length and 25.4 mm in width.
Red dot sights compatible with the adapter plate Type 3
| Red Dot | Product | Details |
|---|---|---|
| Holosun SCS 320 | ||
| Leupold DeltaPoint Pro |
Type 4 adapter plate is designed for the C-more mounting standard. The plate measures 48 mm in length and 25.4 mm in width.
Red dot sights compatible with the adapter plate Type 4
Type 5 adapter plate is designed for the Shield RMS/SMS mounting standard. There is a raised section on both the front and the rear part of the plate. The space in between the raised sections measures 43 mm in length. The plate measures 25.4 mm in width.
Red dot sights compatible with the adapter plate Type 5
Note: The following red dot sights are also compatible with type 5 adapter plate, but to mount them, the rear two pins must be filed off.
| Red Dot | Product | Details |
|---|---|---|
| Holosun 407K | Discontinued | |
| Holosun 507K | Discontinued | |
| Holosun 407K X2 | ||
| Holosun 507K X2 |
Converter plate mounting options
Note: Using a converter plate results in a high-profile setup of the red dot sight.
Shield RMS/SMS to Trijicon RMRcc
This converter plate can be mounted on the type 5 adapter plate supplied with Arex Delta M Gen II. It converts the Shield RMS/SMS mounting standard to the Trijicon RMRcc mounting standard, allowing the use of following red dot sights on Arex Delta M Gen II:
Trijicon RMR to Holosun 509
This converter plate can be mounted on the type 2 adapter plate supplied with Arex Delta M Gen II. It converts the Shield RMS/SMS mounting standard to the Holosun 509 mounting standard, allowing the use of following red dot sights on Arex Delta M Gen II:
Trijicon RMR to Aimpoint Acro
This converter plate can be mounted on the type 2 adapter plate supplied with Arex Delta M Gen II. It converts the Shield RMS/SMS mounting standard to the Holosun Acro mounting standard, allowing the use of following red dot sights on Arex Delta M Gen II:
| Red Dot | Product | Details |
|---|---|---|
| Acro C-1 | ||
| Acro C-2 | ||
| Acro P-1 | ||
| Acro P-2 | ||
| Steiner MPS | ||
| Vector Optics Frenzy Plus 1x18x20 |
If you manufacture adapter plates for this pistol and are interested in cooperation with us, send an e-mail to [email protected].
Hello where can i buy a mount for arex delta gen II M type 5?
You can get them directly from Arex:
https://www.arex-store.si/product-page/delta-gen-2-or-plates
Hi. Does any optics fit directly without plate?
No, as far as we’re aware, there isn’t one.
Hi! How can I find a mount plate to use a Holosun 507k for Arex Delta Gen I ? Thank you, it’s a good article.