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SI designs rugged, user-focused firearm components and optics. They make accessories like slide plates, charging handles, barrel clamps, red dots, and shotgun parts.
All SI Products (2,383)
Sinclair INTERNATIONAL OFFSET SCOPE LEVEL 1" MATTE BLACK
Sinclair INTERNATIONAL PRIMER POCKET UNIFORMER CARBIDE LARGE RIFLE
Sinclair INTERNATIONAL SHARKFIN CLAMP ATTACHMENT
Sinclair INTERNATIONAL NECK TURNING HANDLE STANDARD 17-338 CALIBER
Sinclair INTERNATIONAL DIE LOCK RING PLIERS FOR REDDING
Sinclair INTERNATIONAL NECK TURNING CASE HOLDER #3 308 FAMILY
Sinclair International Neck Turning Case Holder Magnum
Sinclair INTERNATIONAL NECK TURNING CASE HOLDER #1 223 FAMILY
Sinclair INTERNATIONAL CASEHOLDER DRIVER
Sinclair INTERNATIONAL LARGE CALIBER STAINLESS EXPANDER MANDREL 35 CALIBER (.357")
Sinclair INTERNATIONAL RELOADING DIE SHIMS FITS 7/8"-14" DIES
Sinclair INTERNATIONAL STAINLESS STEEL EXPANDER MANDREL 22 CALIBER (.223")
Sinclair INTERNATIONAL NECK TURNING MANDREL SS 6MM (.241")
Sinclair INTERNATIONAL NECK TURNING MANDREL SS 22 CALIBER (.222")
Sinclair INTERNATIONAL NECK TURNING MANDREL SS 30 CALIBER (.306")
Sinclair International Expander Mandrel 30 Cal Stainless
Sinclair INTERNATIONAL STAINLESS STEEL EXPANDER MANDREL 6MM (.242")
Sinclair INTERNATIONAL NECK TURNING MANDREL SS 6.5MM (.262")
Sinclair INTERNATIONAL STAINLESS STEEL EXPANDER MANDREL 6.5MM (.263")
Sinclair International 7mm Stainless Expander Mandrel
Sinclair INTERNATIONAL STAINLESS STEEL EXPANDER MANDREL 270 CALIBER (.276")
Sinclair INTERNATIONAL NECK TURNING MANDREL SS 338 CALIBER (.336")
Sinclair INTERNATIONAL PILOT STOP STAINLESS STEEL 22 CALIBER
Sinclair INTERNATIONAL PILOT STOP STAINLESS STEEL 44 CALIBER
Sig SAUER, INC. P250/P320FS EXTENDED MAGAZINE 9MM LUGER 30RD BLACK 3/PACK
Sig Sauer P250 P320 9mm 21Rd Coyote High Cap Mag 3 Pack
Sig SAUER, INC. P250/P320-X COMPACT MAGAZINE 9MM LUGER 12RD BLACK 3/PACK
Sig SAUER, INC. P250/P320 FS MAGAZINE 9MM LUGER 17RD COYOTE 3/PACK
Sig SAUER, INC. P250/P320 FS MAGAZINE 9MM LUGER 17RD BLACK 3/PACK
Sig SAUER, INC. P250/P320 FS MAGAZINE 9MM LUGER 10RD COYOTE 3/PACK
Sig SAUER, INC. P250/P320 FS MAGAZINE 9MM LUGER 10RD BLACK 3/PACK
Sig SAUER, INC. P250/P320 COMPACT MAGAZINE 9MM LUGER 15RD BLACK 3/PACK
Sig SAUER, INC. P250/P320 COMPACT MAGAZINE 9MM LUGER 10RD BLACK 3/PACK
SIG SAUER, INC. P365-AXG LEGION MAGAZINE 9MM LUGER 17RD BLACK 3/PACK
Sig Sauer MIX8900250 9mm 10Rd Black P365X XL Magazine
Sig SAUER, INC. P365 MAGAZINE 9MM LUGER 10RD BLACK 3/PACK
Sig SAUER, INC. P365/X/XL MAG W/FINGER EXTENSION 9MM LUGER 12RD BLACK 3/PACK
Sig SAUER, INC. P365 MAG W/FINGER EXTENSION 9MM LUGER 10RD BLACK 3/PACK
SIG SAUER, INC. P365/X/XL/XMACRO MAGAZINE 9MM LUGER 17RD COYOTE 3/PACK
SIG SAUER, INC. P365/X/XL/XMACRO MAGAZINE 9MM LUGER 17RD BLACK 3/PACK
Sig SAUER, INC. MARKSMAN ELITE 308 WINCHESTER 168GR MATCH OTM 200/CASE
Sig SAUER, INC. ELITE MATCH GRADE 223 REMINGTON 77GR MATCHKING OTM 200/CASE
Sig SAUER, INC. MARKSMAN ELITE 6.5 CREEDMOOR 140GR MATCH OTM 200/CASE
Sig SAUER, INC. MARKSMAN ELITE 308 WINCHESTER 175GR MATCH OTM 200/CASE
Sig SAUER, INC. MPX-COPPERHEAD 9MM LUGER 3.5" BBL (1)20RD MAG COYOTE
Silvana Garment Carrier Black Backpacks Totes Luggage
Sig Sauer P365/X/XL Handgun Magazine 9mm Luger 12/rd
Sierra GameKing Rifle Bullets .30 cal .308 205 gr HPBT/CN 500/ct
About SI
Headquarters
Established
-
Country of Origin
USA
History & Heritage
SI began as an American aftermarket parts maker aimed at providing functional, affordable upgrades and accessories for shooters. Over time the brand expanded its offerings across pistol, rifle, and shotgun platforms, becoming known for practical designs and broad compatibility.
Notable Products
Popular items include charging handles, slide adapter plates, red dot sights, barrel clamps, and shotgun conversion components.
Why Choose SI?
Choose SI for straightforward, well-engineered accessories that improve usability and durability without unnecessary complexity.
Hot SI Items June 2026
Trending right now based on the last 30 days of TheGunDock orders + page views.
SilencerCo Sparrow 22 Rimfire Suppressor 22LR 5.08" Stainles
SIG SAUER 322C-ROSE-RS P322 Rose 22 LR 4" Black Anodize Semi
Sig Sauer W365XL-9-BXR3P-MS P365 XL 9mm 3.7" Nitron Semi-Aut
Sig Sauer Tango-MRS Compact Rifle Scope 1-6x24 30mm SFP BDC6
Sig Sauer Cross Sawtooth Rifle 6.5 PRC 22 inch Moss Green Fo
Sierra Bullets 4540C 7mm 0.284 Caliber 140 Grain Tipped Boat
SilencerCo AC1278 ASR Black Nitride 9/16"x24 LH Threads 30 C
Sig SAUER Mags 9MM 20Rd Blue P226 MAG-226-9-20
Shop SI Products
Sig SAUER MCX-SPEAR 6.8x51mm SBR 13in Semi-Auto Rifle RSPEAR
SilencerCo Sparrow 22 Rimfire Suppressor 22LR 5.08" Stainles
Sig Sauer P320 FLUX 9MM 3.9" 30RD Legion 320
Sig Sauer SLH300TIQD 300 Blackout Titanium Suppressor
SilencerCo Velos LBP 5.56 NATO/.223 4.76 In Low Back-Pressur
SIG SAUER MCX Spear SBR 7.62x51mm 13" Nitride NFA
Sig Sauer P365X Macro Tacops 9mm 3.7" 17rd Pistol
Sinclair INTERNATIONAL DIAL INDICATOR .001
Sig Sauer ROMEO1 Black Shroud Kit SOR1SK001: Medium Size, Ne
Sig Sauer 8900823 LTXG Grip Module Laser Engraved P320-X Car
Sig Sauer MCX-SPEAR LT AR Conversion Kit 5.56 NATO 11.5" Bla
Sig SAUER MCX 5.56 NATO 16in 30rd IR Cerakote FDE Rifle RMCX
SI News & Articles
Firearm Shipping Restrictions by State (2026 Update)
State-by-state guide to firearm and ammunition shipping for online buyers and FFL dealers. Current as of May 2026. Cover...
Damaged in Transit: How TheGunDock Handles Shipping Claims on Firearms and Ammo
When a firearm or ammo shipment arrives damaged, the claim process matters. TheGunDock walks through what to do, what we...
The Springfield KUNA: Roller-Delayed 9mm Pistol That's Shaking Up the PDW Market
The Springfield Armory KUNA — a roller-delayed 9mm pistol built in partnership with Croatia's HS Produkt — has becom...
The Strait of Hormuz: 2,500 Years of Trade, Arms, and Conflict
A twenty-one-mile-wide choke point has shaped the movement of goods — and weapons — across half the ancient and mode...
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Choose SI for straightforward, well-engineered accessories that improve usability and durability without unnecessary complexity....
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