A pin-and-weld muzzle device is permanently attached to the barrel, so it counts toward barrel length. That lets a short barrel reach the 16" federal rifle minimum.
Do I still need this after October 9?
Often, yes. A rifle with a barrel under 16" is still a short-barreled rifle under federal law. ATF has only stopped enforcing NFA registration for SBRs. Under the Gun Control Act, you still need ATF approval to take an SBR across state lines, and some state laws still treat SBRs differently. Pinning to 16" sidesteps both.
Pick by barrel length
| Your barrel | Device | Device length | Finished length |
|---|---|---|---|
| 13.7" | Eclipse 13.7" Pin and Weld | 3.05" | 16.1" |
| 14.5" | Eclipse 14.5" Pin and Weld | 2.25" | 16.1" |
The Eclipse-L (2.1") is too short to bring a 14.5" barrel to 16". Do not pin and weld it.
Both versions
Both have a square shoulder, a .30 cal bore, 360-degree ports, a 3/32" pin hole, and a .900"-24 interface for Q Plan-B and Rearden Atlas mounts. Note: the 13.7" version is not compatible with Q silencers; it bottoms out on their blast baffle.
Have it done right
Use a qualified gunsmith to pin and weld, and have them confirm the finished length. Once pinned, the device is not returnable.
Shop related: Muzzle devices
Related reading: Which LPM Muzzle Devices Fit Your Mount?
Which LPM Muzzle Devices Fit Your Mount?
1/2-28 vs 5/8-24: A Thread Pitch Guide