Independent field journal · Practice, evidence, judgmentIssue No. 01 / Summer 2026
KGKNOWN GROUNDClarity and capability in a contested world
Newsletter
Compatibility desk

Build the mounting path.

Choose the exact factory optic-ready pistol. Known Ground separates direct fits from plate-required combinations and leaves uncertain fitment honestly unverified.

Step one

Select the exact pistol.

MOS, A-CUT, Gen6, DPO, and HOST are separate systems. Choose what is marked on or supplied with your pistol.

Selected system

Echelon 4.0C

Springfield Echelon VIS · VIS

Variable Interface System with optic-specific pin and screw sets.

System checked Jul 15, 2026Manufacturer source ↗
Step two

Browse the optic lineup.

Filter by manufacturer to see every cataloged optic, including combinations that still need verification.

Useful fits first

Direct mount

No separate adapter plate is required. Always confirm the specified screws and torque.

Direct mount

Holosun EPS

Mounting footprint: Holosun K / RMSc family · checked Jul 16, 2026 · footprint source ↗

Direct VIS mount.

Hardware: Pin set 3; optic-manufacturer screws may require modification.

Not personally tested · manufacturer verified · checked Jul 15, 2026

Direct mount

SIG Sauer ROMEO2

Mounting footprint: SIG PRO / DPP family — verify recoil bosses · checked Jul 16, 2026 · footprint source ↗

Direct VIS mount.

Hardware: Pin set 2; optic-manufacturer screws.

Not personally tested · manufacturer verified · checked Jul 15, 2026

Plate required

These combinations require the exact plate or mounting kit shown with the optic.

Plate required

Aimpoint ACRO P-2

Mounting footprint: Aimpoint ACRO · checked Jul 16, 2026 · footprint source ↗

VIS ACRO plate required.

Hardware: Follow VIS ACRO plate instructions.

Not personally tested · manufacturer verified · checked Jul 15, 2026

Required mounting path
OEM / factory

Springfield Armory Springfield VIS ACRO Plate

Manufacturer-listed mounting plate or kit.

Checked Jul 15, 2026 · Not personally tested

Plate required

Steiner MPS

Mounting footprint: Aimpoint ACRO · checked Jul 16, 2026 · footprint source ↗

VIS ACRO plate required.

Hardware: Follow VIS ACRO plate instructions.

Not personally tested · manufacturer verified · checked Jul 15, 2026

Required mounting path
OEM / factory

Springfield Armory Springfield VIS ACRO Plate

Manufacturer-listed mounting plate or kit.

Checked Jul 15, 2026 · Not personally tested

Incompatible and unverified optics 30
unverified

Aimpoint COA

Mounting footprint: Aimpoint A-CUT / COA · checked Jul 16, 2026 · footprint source ↗

No verified fitment evidence is on file for this combination.

Not personally tested · unverified · checked Not yet verified

unverified

Holosun 407C X2

Mounting footprint: Trijicon RMR · checked Jul 16, 2026 · footprint source ↗

No verified fitment evidence is on file for this combination.

Not personally tested · unverified · checked Not yet verified

unverified

Holosun 407C X3

Mounting footprint: Trijicon RMR · checked Jul 16, 2026 · footprint source ↗

No verified fitment evidence is on file for this combination.

Not personally tested · unverified · checked Not yet verified

unverified

Holosun 407COMP

Mounting footprint: Trijicon RMR · checked Jul 16, 2026 · footprint source ↗

No verified fitment evidence is on file for this combination.

Not personally tested · unverified · checked Not yet verified

unverified

Holosun 407K X2

Mounting footprint: Holosun K · checked Jul 16, 2026 · footprint source ↗

No verified fitment evidence is on file for this combination.

Not personally tested · unverified · checked Not yet verified

unverified

Holosun 507-PROMAX

announced

Mounting footprint: Trijicon RMR · checked Jul 16, 2026 · footprint source ↗

No verified fitment evidence is on file for this combination.

Not personally tested · unverified · checked Not yet verified

unverified

Holosun 507C X3

Mounting footprint: Trijicon RMR · checked Jul 16, 2026 · footprint source ↗

No verified fitment evidence is on file for this combination.

Not personally tested · unverified · checked Not yet verified

unverified

Holosun 507COMP

Mounting footprint: Trijicon RMR · checked Jul 16, 2026 · footprint source ↗

No verified fitment evidence is on file for this combination.

Not personally tested · unverified · checked Not yet verified

unverified

Holosun 507K X2

Mounting footprint: Holosun K · checked Jul 16, 2026 · footprint source ↗

No verified fitment evidence is on file for this combination.

Not personally tested · unverified · checked Not yet verified

unverified

Holosun 509T X2

Mounting footprint: Holosun 509T · checked Jul 16, 2026 · footprint source ↗

No verified fitment evidence is on file for this combination.

Not personally tested · unverified · checked Not yet verified

unverified

Holosun AEMS-MACRO

announced

Mounting footprint: Holosun 509T · checked Jul 16, 2026 · footprint source ↗

No verified fitment evidence is on file for this combination.

Not personally tested · unverified · checked Not yet verified

unverified

Holosun AEMS-MICRO

announced

Mounting footprint: AEMS-MICRO proprietary · checked Jul 16, 2026 · footprint source ↗

No verified fitment evidence is on file for this combination.

Not personally tested · unverified · checked Not yet verified

unverified

Holosun DPS-TH

announced

Mounting footprint: Holosun 509T · checked Jul 23, 2026 · footprint source ↗

No verified fitment evidence is on file for this combination.

Not personally tested · unverified · checked Not yet verified

unverified

Holosun EPS CORE

announced

Mounting footprint: Shield RMSc · checked Jul 16, 2026 · footprint source ↗

No verified fitment evidence is on file for this combination.

Not personally tested · unverified · checked Not yet verified

unverified

Holosun EPS CORE MRS

announced

Mounting footprint: Shield RMSc · checked Jul 23, 2026 · footprint source ↗

No verified fitment evidence is on file for this combination.

Not personally tested · unverified · checked Not yet verified

unverified

Holosun EPS Carry

Mounting footprint: Holosun K · checked Jul 16, 2026 · footprint source ↗

No verified fitment evidence is on file for this combination.

Not personally tested · unverified · checked Not yet verified

unverified

Holosun SCS 320

Mounting footprint: SIG P320 / DPP family · checked Jul 16, 2026 · footprint source ↗

No verified fitment evidence is on file for this combination.

Not personally tested · unverified · checked Not yet verified

unverified

Holosun SCS Carry

Mounting footprint: Holosun K / RMSc adapter · checked Jul 16, 2026 · footprint source ↗

No verified fitment evidence is on file for this combination.

Not personally tested · unverified · checked Not yet verified

unverified

Holosun SCS MOS

Mounting footprint: Glock MOS direct · checked Jul 16, 2026 · footprint source ↗

No verified fitment evidence is on file for this combination.

Not personally tested · unverified · checked Not yet verified

unverified

Holosun SCS MP2

Mounting footprint: S&W M&P M2.0 direct · checked Jul 16, 2026 · footprint source ↗

No verified fitment evidence is on file for this combination.

Not personally tested · unverified · checked Not yet verified

unverified

Holosun SCS PDP

Mounting footprint: Walther PDP 2.0 direct · checked Jul 16, 2026 · footprint source ↗

No verified fitment evidence is on file for this combination.

Not personally tested · unverified · checked Not yet verified

unverified

Holosun SCS VP9

Mounting footprint: HK VP9 OR direct · checked Jul 16, 2026 · footprint source ↗

No verified fitment evidence is on file for this combination.

Not personally tested · unverified · checked Not yet verified

unverified

SIG Sauer ROMEO-X Enclosed Pro

Mounting footprint: DeltaPoint Pro · checked Jul 16, 2026 · footprint source ↗

No verified fitment evidence is on file for this combination.

Not personally tested · unverified · checked Not yet verified

unverified

SIG Sauer ROMEO-X Pro

Mounting footprint: DeltaPoint Pro · checked Jul 16, 2026 · footprint source ↗

No verified fitment evidence is on file for this combination.

Not personally tested · unverified · checked Not yet verified

unverified

SIG Sauer ROMEO1Pro

Mounting footprint: SIG PRO / DPP family · checked Jul 16, 2026 · footprint source ↗

No verified fitment evidence is on file for this combination.

Not personally tested · unverified · checked Not yet verified

unverified

Trijicon RCR

Mounting footprint: RMR-pattern / RCR hardware · checked Jul 16, 2026 · footprint source ↗

No verified fitment evidence is on file for this combination.

Not personally tested · unverified · checked Not yet verified

unverified

Vortex Defender-CCW

Mounting footprint: Shield RMSc · checked Jul 16, 2026 · footprint source ↗

No verified fitment evidence is on file for this combination.

Not personally tested · unverified · checked Not yet verified

unverified

Vortex Defender-CCW Enclosed Solar

Mounting footprint: Shield RMSc · checked Jul 16, 2026 · footprint source ↗

No verified fitment evidence is on file for this combination.

Not personally tested · unverified · checked Not yet verified

unverified

Vortex Defender-ST Enclosed Solar

Mounting footprint: DeltaPoint Pro · checked Jul 16, 2026 · footprint source ↗

No verified fitment evidence is on file for this combination.

Not personally tested · unverified · checked Not yet verified

unverified

Vortex Defender-XL

Mounting footprint: DeltaPoint Pro · checked Jul 16, 2026 · footprint source ↗

No verified fitment evidence is on file for this combination.

Not personally tested · unverified · checked Not yet verified

Use this carefully

Compatibility is not a recommendation.

Model revisions, screw length, plate revisions, and supplied hardware can change. Confirm the exact manufacturer instructions before mounting or using equipment.

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