Best Red Dot For P320 X5 Legion & Aftermarket Optic Plates

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Referenced Roger Barrera (Get This Gun Today!)

In this buying guide, let’s check out some of the best red dots for P320 X5 pistol.

Out of all the products we have tested, the large windowed red dot like the Leupold DeltaPoint 2 and Trijicon SRO are our favorites for fast sight acquisition without losing the dot, and there are other great ones we want to show.

P320 X5 is more geared towards competition shooting, so a large FOV optic helps the shooter to acquire targets faster and more accurately.

In addition, this guide will talk about the P320 X5’s optic compatibility issues, co-witness, and aftermarket optic plates.

Many people seemed to have issues with the gun’s optic compatibility & co-witness, which have generated many threads around this topic.

Let’s check it out…


3 Best Red Dot Optics For P320 X5 Legion

The P320 X5 Legion slide is made to fit ROMEO1 PRO & Leupold DeltaPoint PRO ONLY, and it doesn’t come with additional mounting plates.

Since some people are having problems with the ROMEO1. We don’t recommend any of these two sights AT ALL for fitting, cost & poor durability reasons [Watch ROMEO1 Breaking From Drop Test]

There are so many other higher-quality optics for this gun that people should go after and be happy with, so check them out below:


  • Features:2 MOA dot (Red/Green), Motion activated, Fully multi-coated lens, Grade 5 Titanuim housing, CR2032 Battery, 1 MOA/click adjustment
  • Benefits:Fast on target with wide field of view, Solar + battery power providing ~100K hours, Use same mount profile as Trijicon RMR
  • MUST have Mount: Springer Precision RMR Mount

  • Features:2.5 MOA dot, Anti-reflective lens, 1 MOA/click adjustment, Battery saving motion sensor
  • Benefits:Fast TGT acquisition, Perfect for competition, Tool-less top loading battery access, Rugged for home defense
Sig Sauer Romeo3XL 1x35mm Red Dot Sight, 3 MOA Dot Reticle, Aircraft Grade Aluminum, Black, SOR31004
  • Features:1X35mm, 3 MOA dot,  MOTAC, Side loading CR2032 battery tray
  • Benefits:Largest FOV, Fast TGT acquisition for speed and accuracy, Easier battery loading from the side
  • MUST have Mount: Springer Precision ROMEO3 XL Mount

Leupold DeltaPoint Pro – Best Overall

sig p320 x5 with deltapoint pro red dot
Image Referenced ParkerMountainMachine

Since the X-Five Legion slide is already cut for the Leupold DeltaPoint Pro specifically, this optic is the best large window optic for this gun without additional modification.

For the money, this optic lasts way better than Sig Optics and it’s a great competition optic.

Besides that… the top-loading battery access makes battery swap easy without sight removal.

Trijicon SRO – Great Optic, But Causes Ejection Issue

Trijicon SRO interferes P320 X5 ejection
Image Referenced

If we had to pick between the DeltaPoint Pro or the Trijicon SRO, we had to go with the DeltaPoint Pro because of the extended length of the SRO body interferes with shell ejection as it sits too close over the ejection port.

ROMEO3XL 1X35mm – Largest FOV

sig p320 with ROMEO3 XL open reflex sight

If you’re a hardcore Sig fan who wants the entire pistol setup top to bottom to be Sig Sauer, then the ROMEO3XL is the optic for you.

What’s unique about the ROMEO3XL is its large 1X35mm lens as an open emitter reflex optic, which means the shooter will have an easier time picking up the dot within the window, and also track the dot better.

In general, the ROMEO3XL is stronger and higher quality than the ROMEO1, and you get what you pay, which is a fairly durable optic with all the features like MOTAC, IPX7 waterproof, and others.

What we like most about this optic is its large 1X35mm window and its side battery loading tray for easier battery access without sight removal or anything like that.

Great for setting up a 100% Sig Sauer branded competition gun when shooting the P320 X5 Legion.

Holosun HS508T – Most Durable

p320 x5 tan with holosun 507c
Image Referenced OuterImpact

Holosun has been the leader in making great optics, very soon it will be added to the list of high-end optics alongside Aimpoint and Trijicon.

For the price, durability, and functionality the overall quality of the HS508T is superior among other non-military contracted optics.

The Holosun HS508T is the upgraded version of the HS507C, and it retains the same features but this time it’s built with Grade 5 titanium alloy, which is ~35% stronger than 7075 T6 aluminum without adding extra weight.

What’s great for the P320 X Five is its reticle selections, where a new shooter can use the 50 MOA ring as the training wheel reticle for practicing sight acquisition. Once the shooter is comfortable, he/she has the option to switch to the 2 MOA center dot.

When mounting to the P320 X5 Legion, be sure to purchase the aftermarket mounting plates from Springer Precision here.

Preview Product Rating
HOLOSUN HE508T-RD Red Dot Sight HOLOSUN HE508T-RD Red Dot Sight 51 Reviews

How To Fix P320 X5 Legion Optics Compatibility Issue

Colin Noir shooting P320 with Romeo1
Image Referenced Colin Noir

Note: The original P320 X5 (non-Legion version) still works with Sig ROMEO1 (non-Pro version)

The biggest problem Sig Sauer ROMEO1 (non-pro) users are having is the fit issue on the new P320 X5 Legion. The X5 Legion slide has a footprint cut to accommodate the Sig ROMEO 1 Pro and Leupold DeltaPoint Pro due to the military’s optic requirement.

The original ROMEO 1 (SOR11000) has a smaller footprint, and the mounting holes are too small for proper mounting using the M4 screws.

Non-Legion P320 X5 Universal Optic Adapter

Can you put a red dot on a SIG P320 and expect it to work flawlessly?

Well… there were some issues, and we can fix it with a aftermarket adapter plate.

NOTE: If you already own the original P320 X5, it’s probably a better idea to just get this optic adapter here: Outerimpact P320 X5 Optic Adapter

**DOES NOT FIT X-5 LEGION or X Carry**

But wait… there is more

Aftermarket Optic Mounting Adapter For P320 X5 Legion

For X-Five Legion Users! X-Five Legion users need the M17 optic plates from Outerimpact’s website along with some additional screws.

The Sig Sauer P320 series handgun doesn’t come with optic adapter plates for other optics besides Sig ROMEO 1 and Leupold DeltaPoint.

If you’re using any other optics like Holosun, Burris, Trijicon…etc you have to get the adapter plates from either from Outerimpact or SpringerPrecision.

We highly recommend the Outerimpact universal P320-M17/X5 mount as it can accept over 15 popular micro red dot optics.

For Non-Legion P320 X5, please use this mount from Outerimpact:

Custom Fitting Maybe Required (Springer Precision)

Due to variances in the slide cut and a required tight fit, some minor fitting may be needed to install the mount.  A file is recommended for fitting.

Wrap Up

The P320 XFive Legion is a very hyped up gun for its competition optimized features. Overall it shoots great with its improved trigger

As far as optic goes, the ROMEO1 and ROMEO1 Pro are just a total disaster, which leaves shooters almost no confidence buying these products due to its poor quality and fitting issues.

For the money, it’s almost not worth buying the X5 Legion & a $400 ROMEO1 Pro optic for it. The best optic we really recommend is the Holosun 507C and Leupold DeltaPoint Pro for being way more durable and affordable.

Be sure to check out Outerimpact & Springer Precision for an RMR mount adapter for the Holosun 507C as they share the same mounting dimension.

Hope you find this interesting and helpful, please check out other content on our site.

Sig Sauer P320 X5 Legion Optics FAQ

Popular P320 X5 Legion optics related questions answered below:

How To Co-Witness With ROMEO 1 Pro On X-Five?

The Sig Romeo 1 Pro comes with co-witness rear two dotted sight as a part of the optic, but it sits too low.

Unlike using suppressor sights where you can clearly line up the optic and iron sights.

What’s Different? P320 X-Five Legion VS Standard X-Five

There are significant difference between the two pistol models.

Frame Module
THe P320 X-Five Legion is noticeably heavier due to the new tungsten infused grip module compared to the polymer frame.

Optic Cuts
X5 Legion’s optic cut is different than the standard X5. The Legion slide was cut for ROMEO1 PRO & Leupold DeltaPoint Pro. P320 X-Carrys will have the same cut as Legion models.

X5 Legion has a 30% lighter trigger than the original model, which is made for competition use.

What To Do If ROMEO1 Optic Doesn’t Fit X5 Legion?

Since Sig Sauer has made it clear that original Sig ROMEO doesn’t fit on the X5 Legion slide, which means you have to buy ROMEO1 Pro to make it work.

Sadly Sig doesn’t provide other mounting plates for optics like RMR, Burris, Vortex and others.

If you really like the Sig Sauer branded optic on the X-5 Legion, then return the ROMEO1 and swap for the ROMEO1 Pro, which will cost you ~$200 more.

If you don’t want Sig Optics, then there are plenty of other choices out there, but be sure to buy aftermarket optic adapter sold from Springer Precision Inc or Outerimpact.

How To Remove P320 X5 Optic Cover Plate?

For some reason, the Sig P320 X5’s optic cover plate is not so intuitive to take it off just by looking at it for the first timer.

The only way to remove it is by taking the slide off and access the mounting screws from the bottom of the slide.

You have to remove the plunger, which blocks access to one of the screws. Once you have removed the cover plate, be sure to place the plunger, spring, extractor, and back, and then you can install any optic normally from the top of the slide.

Check Out: Best Handgun Red Dot Sights

Ying Xu

US Air Force veteran nuclear weapon officer. Aerospace engineering bachelor's degree from the University of Kansas. Experienced as a certified NRA range safety officer. Working as a search engine expert for