Quick answer
Mount the Thorntail X QD Sling Mount onto any 1913 rail section, orienting the 45-degree offset for your preferred sling side, then torque the mounting screw to spec. The process takes under five minutes with a single hex key.
Why the 45-degree offset matters
The Thorntail X is designed with a 45-degree offset from the rail, which keeps the QD socket closer to the rifle's profile than a straight 90-degree mount. This reduces snagging on gear and makes the sling attachment point less obtrusive during movement or storage.
Because the offset is fixed, you need to decide which side of the rifle the mount will live on before tightening. The mount is ambidextrous, but the offset direction is not reversible without flipping the entire mount upside down, which may interfere with rail clearance on some handguards.
Choosing the right rail position
The mount attaches to any 1913 Picatinny slot. For a two-point sling, common positions are near the receiver on the handguard or just behind the front sight base. On shorter rails, you may need to mount it further back to keep the sling swivel from contacting the barrel or gas block.
Test-fit the mount in a few slots before tightening. The anti-rotational tab on the mount must seat fully into the rail slot; if it sits on top of a rail cross-slot, the mount will not hold zero orientation under load.
Installation steps
- 1. Gather tools and inspect the mount: You need a 3/16-inch hex key (or the appropriate size for your mount's screw). Check that the QD socket spins freely and that the anti-rotational tab on the bottom of the mount is clean and undamaged. A damaged anti-rotational tab can cause the mount to rotate under load, so replace the mount if the tab is bent or broken.
- 2. Choose your rail slot and orientation: Slide the mount onto the 1913 rail with the QD socket facing the direction you want the sling to angle. The 45-degree offset should point away from the rifle's side—toward the muzzle or receiver depending on your setup. Tighten the screw just enough to hold the mount in place without fully torquing. If the offset points into the rifle, the sling swivel may bind against the rail or handguard. Reverse the mount if needed before final tightening.
- 3. Torque the mounting screw: Use the hex key to tighten the screw until the mount is snug against the rail. Do not overtighten—the mount should not rock or shift when you apply hand pressure, but the screw should not strip the threads. A torque of about 15 in-lbs is typical, but if you don't have a torque wrench, tighten until the mount is firm and then stop. Overtightening can strip the screw head or damage the rail. If the mount feels loose after a few range sessions, re-torque rather than tightening past the initial setting.
- 4. Attach your QD sling swivel: Press the QD swivel into the socket until you hear or feel it click. Give the sling a firm tug to confirm the swivel is locked. The anti-rotational feature will keep the swivel from spinning, but the mount itself should not rotate on the rail. If the swivel does not click into place, the socket may be obstructed. Check for debris or a damaged swivel ball. Never use a sling without confirming the swivel is locked.
- 5. Test the setup under tension: With the sling attached, apply light pressure in the direction the sling will pull during use (e.g., from the support hand side). The mount should remain stationary on the rail. If it shifts, remove the mount and check that the anti-rotational tab is seated in a full rail slot, not a cross-slot. A mount that shifts during testing will likely fail under real use. Re-position it in a different rail slot if necessary.
Product details
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Thorntail X QD Sling Mount: The Thorntail X 1913 QD Sling Mount provides a 45-degree offset for a lower profile, ambidextrous, snag resistant, anti-rotational QD Swivel Socket attachment point. The 45-degree offset keeps your sling attachment low-profile and snag-resistant, while the anti-rotational design prevents the mount from shifting during use.
Thorntail X QD Sling Mount
