Buy SI Online
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 (2,385)
Sierra 1742 MatchKing 6.5 Creedmoor .264 142gr HPBT 100 Per Box
Sierra 6.5mm 140 Grain HPBT MatchKing Rifle Bullets
Sierra 1730 GameKing 6.5 Creedmoor .264 140gr Spitzer BT (SBT) 100 Per Box
Sierra 1729 MatchKing 6.5 Creedmoor .264 130gr HPBT 100 Per Box
Sierra 1728 GameKing 6.5 Creedmoor 130gr HPBT Bullets 100/Box
Sierra 6.5mm 123gr HPBT Match Bullets 100ct (.264) 1727
Sierra 1725 MatchKing 6.5 Creedmoor .264 120gr HPBT 100 Per Box
Sierra 1720 Pro-Hunter 6.5 Creedmoor .264 120 gr Spitzer 100 Per Box
Sierra 1715 MatchKing 6.5 Creedmoor 107gr HPBT Bullets 100/Box
Sierra 1710 Varminter 6.5 Creedmoor .264 100 gr HP 100 Per Box
Sierra 1630 GameKing 25 Cal 117gr Spitzer Boat Tail Bullets 100/Box
Sierra 1628 MatchKing 25 Cal .257 100 gr HPBT Bullet - 100 Per Box
Sierra 1625 GameKing 25 Cal. .257 100 gr Spitzer BT (SBT) 100 Per Box
Sierra 1616 BlitzKing 25 Cal 90gr Spitzer Boat Tail Bullets 100/Box
Sierra 1615 GameKing 25 Cal .257 90gr HPBT 100 Per Box
Sierra 1610 Varminter 25 Caliber 87 Grain Spitzer Boat Tail 100 Rounds
Sierra 1605 BlitzKing .25 Cal .257 70gr Rifle Bullets 100ct
Sierra 1575 MatchKing 6mm 110gr HPBT 0.243 in 27 in Box of 100
Sierra 1570 MatchKing 6mm .243 107gr HPBT 100 Per Box
Sierra Bullets MatchKing 6mm .243 105gr HPBT 100ct
Sierra 1560 GameKing 6mm .243 100gr Spitzer BT (SBT) 100 Per Box
SIERRA Pro-Hunter 6mm 100Gr Spitzer 100/Box Rifle Bullets (1540)
Sierra 1537 MatchKing 6mm .243 95gr HPBT 100/Bx
Sierra 1530 GameKing 6mm .243 85gr HPBT 100 Per Box
Sierra 1520 Varminter 6mm 85gr Spitzer Bullets 100/Box
Sierra 6mm/243 Caliber 80 Grains Blitz SBT Varminter Bullets (Per 100) 1515
Sierra 1510 Varminter 6mm 75gr Hollow Point Bullets 100/Box
Sierra 1507 BlitzKing 6mm .243 70gr SBT 100 Per Box
SIERRA MatchKing 6mm 70Gr HPBT 100/Box Rifle Bullets (1505)
Sierra 1502 BlitzKing Rifle Bullets 6mm .243 55gr 100ct
Sierra 1500 Matchking Varminter 6mm .243 60gr HP Bullets 100ct
Sierra 1455 BlitzKing .22 Caliber 55 Grain SBT Bullets
Sierra 1450 BlitzKing 22 Caliber 50 Grain Spitzer Boat Tail 100 Rounds
Sierra 1440 BlitzKing .22 Cal .224 40gr Spitzer 100 Per Box
Sierra 1410 MatchKing .22 Cal .224 52 gr HPBT 100 Per Box
Sierra MatchKing 1400 22 Caliber 53 Grain Hollow Point 100 Count
Sierra 1396 MatchKing .22 Cal .224 95gr HPBT Bullets 100ct
Sierra 1395 GameKing .22 Cal .224 65 gr Spitzer Boat-Tail (SBT) 100 Per Box
Sierra 1390 GameKing .22 Cal .224 55 gr HPBT 100 Per Box
Sierra 1385 Varminter .22 Cal .224 40gr HP 100 Per Box
Sierra 1380 MatchKing 22 Cal .224 69gr HPBT 100 Per Box
Sierra 1375 Varminter 22 Caliber 60 Grain Hollow Point 100 Count
Sierra 1370 Varminter 22 Cal .224 63 gr Semi-Pointed (SMP) 100 Per Box
Sierra 1365 GameKing .22 Cal .224 55 gr Spitzer Boat-Tail (SBT) 100 Per Box
Sierra 1360 Varminter 22 Cal 55gr Spitzer Bullets 100/Box
SIERRA GameKing .22 Cal 55Gr FMJBT 100/Box Rifle Bullets (1355)
Sierra 1345 Varminter 22 Cal 55gr Spitzer Blitz 100/Box
Sierra 1340 Varminter 22 Cal 50gr Spitzer Blitz Bullets 100/Box
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.
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
Sig Sauer P365 9mm 3.1 Inch NITRON Striker Fired Compact Han
Sig Sauer P226 X-Five Extreme Semi-automatic Single Action O
Sig Sauer P226 Magazine 10rd 40 S&W/357 SIG Stainless Steel
Sig Sauer WRMCX-556N-9B-LT-SBR MCX SBR 223 Rem | 5.56 NATO 9
Shop SI Products
Sig SAUER MCX-SPEAR 6.8x51mm SBR 13in Semi-Auto Rifle RSPEAR
Sig Sauer P320 FLUX 9MM 3.9" 30RD Legion 320
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
Sierra 1502 BlitzKing Rifle Bullets 6mm .243 55gr 100ct
Sierra MatchKing-X Rifle Bullets .30 Cal 175 gr HPBT 500/ct
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...
Ready to Shop SI?
Choose SI for straightforward, well-engineered accessories that improve usability and durability without unnecessary complexity....
Browse All Products