Which red dots fit a Sig P320 slide?
Sig's optic-ready P320 slides are cut for the Romeo1Pro footprint, which is also the DeltaPoint Pro pattern. Optics with that footprint bolt straight on; RMR-pattern optics need a plate.
The Short Answer
- An optic-ready P320 slide takes Romeo1Pro-footprint optics directly, such as the Romeo1Pro and RomeoX Pro.
- RMR-footprint optics like the Holosun 407C and 507C need an RMR adapter plate, about $40.
- A slide with no optic cut can't take a red dot unless it is milled.
- The optic only cares about the slide. The grip module doesn't change which red dots fit.
Slide and Optic
Every P320 slide we list, checked against every optic.
Sig Sauer P320 Compact Slide Assembly, 9mm
- Won't fit Sig Sauer Romeo1Pro 6 MOA · Sig Sauer RomeoX Pro · Holosun HS407C X2 · Holosun HS507C X2 This slide has no optic cut. Choose an optic-ready slide or skip the optic.
Sig Sauer P320 Compact Slide Assembly, 9mm, Optic Ready
- Fits Sig Sauer Romeo1Pro 6 MOA · Sig Sauer RomeoX Pro
- Check Holosun HS407C X2 · Holosun HS507C X2 This optic uses the RMR footprint. Sig optic-ready slides need an RMR adapter plate (about $40).
Sig Sauer P320 M18 Slide Assembly, 9mm
- Fits Sig Sauer Romeo1Pro 6 MOA · Sig Sauer RomeoX Pro
- Check Holosun HS407C X2 · Holosun HS507C X2 This optic uses the RMR footprint. Sig optic-ready slides need an RMR adapter plate (about $40).
Sig Sauer P320 XFull Slide Assembly, 9mm
- Fits Sig Sauer Romeo1Pro 6 MOA · Sig Sauer RomeoX Pro
- Check Holosun HS407C X2 · Holosun HS507C X2 This optic uses the RMR footprint. Sig optic-ready slides need an RMR adapter plate (about $40).
Sig Sauer P320 Subcompact Slide Assembly, 9mm
- Won't fit Sig Sauer Romeo1Pro 6 MOA · Sig Sauer RomeoX Pro · Holosun HS407C X2 · Holosun HS507C X2 This slide has no optic cut. Choose an optic-ready slide or skip the optic.
Sig Sauer P320 Full Slide Assembly, .45 ACP
- Won't fit Sig Sauer Romeo1Pro 6 MOA · Sig Sauer RomeoX Pro · Holosun HS407C X2 · Holosun HS507C X2 This slide has no optic cut. Choose an optic-ready slide or skip the optic.
Parts Worth a Look
Our picks from the Sig P320 catalog, with the lowest price we list (prices last checked Oct 4, 2026).
Optic
Best Value
Sig Sauer Romeo1Pro 6 MOA
Romeo1Pro footprint · Direct mount
Mounts straight to Sig optic-ready slides, no plate.
$244.99 at Primary Arms (sample price)
Premium Pick
Sig Sauer RomeoX Pro
Romeo1Pro footprint · Larger window
Bigger window, same direct-mount footprint.
$339.99 at OpticsPlanet (sample price)
Slide Assembly
Budget Pick
Sig Sauer P320 Compact Slide Assembly, 9mm
Compact 3.9" · 9mm · No optic cut · SIGLITE sights
Complete slide with night sights.
$249.99 at Sig Sauer (sample price)
Best Value
Sig Sauer P320 M18 Slide Assembly, 9mm
Compact 3.9" · 9mm · Optic ready · Coyote
Army M18 pattern, optic ready, suits the Carry grip.
$379.99 at Sig Sauer (sample price)
Premium Pick
Sig Sauer P320 XFull Slide Assembly, 9mm
Full 4.7" · 9mm · Optic ready
Longest sight radius, optic ready.
$399.99 at Sig Sauer (sample price)
Start from a Complete Build
Every part already checked to fit. Open one in the builder and swap anything you like.
Sources
Updated Oct 5, 2026.