What specific mechanical changes did Sig Sauer implement in the 2017 voluntary upgrade and subsequent P320 revisions?
Executive summary
SIG Sauer’s 2017 voluntary upgrade for the P320 made targeted mechanical alterations: lighter internal components (a thinner-profile trigger, reduced-weight sear and striker) and the addition of a mechanical disconnector, changes SIG says reduce the chance of a drop-induced discharge; the work was performed only at SIG’s factory and was offered free with shipping paid by the company [1] [2] [3]. The revisions were rolled into later production so units manufactured after August 8, 2017 include the change by default, while SIG and outside testers continue to dispute how common the rare drop-firing events actually were [2] [4] [5].
1. The concrete mechanical changes SIG implemented
The headline alterations in the voluntary upgrade were threefold: SIG installed a new thinner-profile, lighter trigger externally and internally, replaced the sear and striker with lighter-weight components, and added a mechanical disconnector into the fire-control system; SIG described these as an “enhanced trigger” system intended to limit rearward trigger movement and add an extra mechanical safeguard [1] [6] [5]. SIG’s own materials emphasize the lighter trigger profile as the most visible external sign and list lighter sear/striker parts and a disconnector as the principal internal modifications [2] [1].
2. How the upgrade was delivered and which guns were affected
SIG ran the change as a voluntary upgrade program beginning August 2017, requiring owners to send pistols to SIG because the work could not be done by third-party gunsmiths or dealers; the company covered the upgrades and return shipping and later noted that pistols manufactured after the program start date already included the modification by default [3] [2] [1]. SIG also temporarily halted production and shipments from its New Hampshire factory while manufacturing changes were implemented, and later reported hundreds of thousands of owners were eligible and over one hundred thousand pistols had been upgraded under the program [7] [1].
3. Why SIG said the changes were necessary — and the competing narrative
SIG framed the revisions as refinement after “specific incidents” and additional internal rough-handling testing that revealed a potential discharge in narrowly defined drop-impact scenarios outside traditional industry test angles; the company stressed the pistol met industry standards and called the program voluntary rather than a recall [4] [3]. Independent drop tests and viral videos that preceded SIG’s announcement had indicated certain drop orientations could produce an unintended discharge, prompting SIG to act; critics and some testers argued those real-world demonstrations exposed a genuine design vulnerability, while SIG pushed back that the pistol cannot discharge without a deliberate trigger pull and said the upgrade was a performance and safety enhancement, not an admission of a pervasive defect [5] [6] [4].
4. Practical effects reported by owners, agencies and SIG
Owners who sent guns in generally reported a perceptible change in trigger feel — often described as lighter take-up, a cleaner reset, loss of a dry-fire “click,” and in some accounts a flatter or thinner trigger face — consistent with the replaced parts SIG identified [8] [9]. SIG maintained the upgraded design improved safety margins, and the M17 military variant was explicitly excluded from the voluntary upgrade because it differed in specification; SIG’s blog and press pieces framed the program as rapid remediation intended to reassure customers and partners [1] [3].
5. What remains disputed or unproven in public reporting
Public reporting and SIG’s statements converge on what was changed physically, but they diverge on the scale and root cause of drop-fire incidents: SIG’s documentation stresses additional testing and argues the pistol met standards and that the upgrade was precautionary, whereas independent videos and testers asserted that real-world drops produced discharges and that retrofits were needed [4] [5] [6]. The sources provided do not contain final, independent adjudications proving that the mechanical changes eliminated all drop-fire risk in every conceivable scenario, so questions about residual risk under extreme abuse remain open in the reporting cited [1] [4].