SIG SAUER P320 Full-Size Recoil Spring Assembly – .357 SIG, .40 S&W, .45 Auto

SIG SAUER P320 Full-Size Recoil Spring Assembly

Maintain a compatible full-size P320 with a genuine SIG SAUER factory recoil spring assembly. Manufacturer part number RSA-320F-4035745 is specified for full-size P320 pistols chambered in .357 SIG, .40 S&W, or .45 Auto. The captured assembly combines the guide rod and recoil spring into a single service component, making it a straightforward replacement for the matching original unit.

Exact caliber and size compatibility

SIG SAUER lists this assembly for full-size P320 models in the three stated calibers. Its published recoil-spring length is 3.81 inches (97 mm). It is not the recoil assembly for a 9mm P320, and it should not be selected for compact, carry, subcompact, or XFive configurations solely because those pistols share the P320 name. Buyers should verify the pistol’s caliber, slide length, exact configuration, and existing assembly before ordering.

Using the correct recoil system matters because the spring assembly helps control rearward slide movement, stores energy during cycling, and returns the slide into battery. A caliber- or length-mismatched assembly can change slide timing and may prevent normal operation. Factory part identification is therefore more reliable than choosing by appearance alone.

Service and replacement use

Recoil springs are working components that compress and extend whenever the pistol cycles. Replacement may be appropriate as part of the maintenance interval recommended by SIG SAUER, when correcting a damaged or missing assembly, or during inspection by a qualified armorer. The need for replacement depends on round count, ammunition, operating conditions, and the condition of the individual firearm rather than appearance alone.

This is a captured factory assembly, which keeps its spring and guide rod together during normal field stripping. It is supplied as one complete recoil spring assembly; a barrel, slide, grip module, firearm, tools, and other internal parts are not included.

Installation and safety

• Unload the pistol completely and remove the magazine before beginning any work.
• Visually and physically confirm that the chamber is empty.
• Follow the current SIG SAUER instructions for the exact P320 configuration.
• Confirm that the assembly is oriented and seated correctly before reassembly.
• Perform all manufacturer-recommended function and safety checks before live fire.

If the pistol’s caliber, slide configuration, or prior parts history is uncertain, consult SIG SAUER or a qualified gunsmith before installation. Do not modify the spring assembly to force compatibility with a different P320 configuration.

Key specifications

• Manufacturer: SIG SAUER
• Manufacturer part number: RSA-320F-4035745
• UPC: 798681556618
• Platform: P320 full-size
• Compatible calibers: .357 SIG, .40 S&W, and .45 Auto
• Published length: 3.81 inches / 97 mm
• Configuration: Captured recoil spring and guide rod assembly
• Quantity: One complete assembly