The SIG Romeo1Pro footprint P320 X-Series factory optic cut
front ↑ Screws per SIG kit
Driver T10
Torque per SIG manual
Pattern proprietary
Diagram is schematic — top-down, optic
front at the top — and is not to scale.
Interface 2 screws, forward lugs — SIG's own pattern
What to know The cut on most optic-ready P320 slides. Everything else mounts to it through a plate, which is why the C&H and SIG adapter market for this cut is so large.
Optics using this footprint Pistols that mount it with no adapter Plates that provide this footprint Slide interface Plate Source GLOCK MOS — standard & full size V4 MIL/LEO (per-footprint SKU) C&H Precision S&W M&P C.O.R.E. / Optics Ready M&P 2.0 → SIG Romeo1Pro C&H Precision SIG Romeo1 cut (P226 / P229 RX Legion) Romeo1 → Romeo1Pro C&H Precision
Check a pairing Use the fit checker to see whether a specific optic and
pistol go together, and what it costs to mount.
Optic Mounting is a reference, not an authority. Footprints, plate numbering and slide cuts
change between generations and production runs of the same model name. Confirm against the current manuals
from both the pistol and optic makers, and against the plate maker's own fitment chart, before buying or
installing. Entries marked Verify are ones where published information
is thin or contested.
Screw length is the failure mode nobody catches. A screw that is too long bottoms out on the slide
or intrudes into the striker channel; one that is too short strips under recoil. Test-fit dry and count
threads. Blue removable threadlocker only, never red.
Safety, and the limits of this site. Confirm the firearm is unloaded before any work on the slide —
drop the magazine, lock the slide back, and check the chamber by sight and by feel. Mounting an optic is
gunsmithing: work within your own competence and use a qualified gunsmith when a job is past it. Information
here is provided as-is, with no warranty of any kind, and you use it at your own risk — Optic Mounting
accepts no liability for damage to a firearm or optic, for injury, or for money spent on parts that turn out
not to fit. Modifying a firearm may also carry legal consequences that vary by state and locality; that is
yours to check.
Data compiled September 2026 from manufacturer documentation and plate-maker fitment
charts. Prices are approximate street-price bands for comparing routes, not for budgeting to the dollar.
Manufacturer and product names are used for identification only; Optic Mounting is not affiliated with,
authorised by or endorsed by any manufacturer, and all trademarks remain the property of their respective
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