The length question is really a barrel nut question

Choosing between a 7" and a 15" AR15 free float handguard is not just about how much rail you want. The barrel nut each handguard ships with is the hard fit checkpoint: if its inside diameter and thread spec do not match your upper and barrel, the length never gets to matter. The two handguards here also use different accessory interfaces, M-LOK on the 7" and KeyMod on the 15", so the comparison splits into fit, interface and build role.

The supplied records give barrel nut dimensions and included hardware but do not give barrel nut torque values, gas block clearance figures or upper receiver compatibility lists. Treat those as checks you confirm against your own upper and barrel before ordering.

7" M-LOK vs 15" KeyMod: the supplied differences

  • Length and weight: The 7" handguard is listed at 0.65 lb. The 15" handguard's weight is not given in the supplied record, so do not assume it scales from the shorter rail.
  • Accessory interface: The 7" uses M-LOK; the 15" uses KeyMod. Your existing accessories decide which interface you can actually use without adapters.
  • Barrel nut inside diameter: The 7" barrel nut is listed at 1.25'' inside diameter; the 15" barrel nut is listed at 1.02'' (26 mm). These are different fit envelopes, not interchangeable numbers.
  • Barrel nut outside diameter: The 7" is listed at 1.375'' (34.4 mm); the 15" is listed at 1.35'' (34.4 mm). Both records give the same metric value, so confirm which figure your handguard channel and wrench actually need.
  • Barrel nut thread spec: Only the 15" record supplies a thread spec: 1-1/4-18 UNC. The 7" record does not state a thread spec, so verify it with the seller before purchase if thread match is critical.
  • Included hardware: The 15" package lists the handguard, barrel nut, 2 crush washers and 6 screws. The 7" record lists the barrel nut as included but does not itemize washers or screws.

Fit numbers for the 7" M-LOK handguard

Fit numbers for the 15" KeyMod handguard

How to pick the length for your build

  • Start with your barrel nut, not the rail: Measure your upper and barrel against the supplied barrel nut inside diameter and thread spec. If neither handguard's nut matches, neither length is the right buy yet.
  • Match the interface to your accessories: If your lights, grips and mounts are M-LOK, the 7" rail avoids adapters. If they are KeyMod, the 15" rail is the direct fit.
  • Use the 7" for compact, weight-conscious setups: At 0.65 lb with the barrel nut included, the 7" M-LOK is the lighter documented option. The supplied record does not state gas block or suppressor clearance, so check those on your own barrel.
  • Use the 15" when you need reach and a known thread spec: The 15" KeyMod is the only one of the two with a stated thread spec (1-1/4-18 UNC) and an itemized hardware list, which helps if you want fewer unknowns before ordering.
  • Do not assume weight scales with length: The 15" weight is not supplied. If weight is a deciding factor, ask the seller for it rather than estimating from the 7" figure.

What the catalog does not settle

Neither record supplies barrel nut torque values, a compatibility list for specific upper receivers, or gas block clearance dimensions. The 7" record also omits a thread spec and an itemized hardware list. Those gaps are not reasons to avoid either handguard, but they are reasons to confirm fit with Texas Precision Optics Inc before ordering, especially on a build where the barrel nut is non-standard.

Both listings note free shipping from Dallas, Texas, with 48 hours of processing and 3-5 business days for delivery. Price is not a substitute for fit: a handguard that does not match your barrel nut costs more in returns than the difference between the two rails.