A reflex suppressor is a suppressor whose tube extends back over the barrel, so part of its volume sits behind the muzzle instead of entirely in front of it. The result is a shorter suppressed firearm for the same barrel length. Chattahoochee Munitions manufactures the PLACID OTB, an all-titanium reflex design for the 12.5-inch CM7S bolt action in 375 Raptor and 458 SOCOM XL.
What Is a Reflex Suppressor?
A conventional suppressor threads onto the muzzle and sits entirely forward of it. A reflex design adds a rearward section, usually a tube, that slides back over the barrel. Gas still exits the muzzle into the baffles in front of it, but the overall package is shorter because some of the suppressor occupies space the barrel already takes up.
Shooters use several names for the same idea: reflex, over the barrel suppressor, OTB suppressor and, for designs where the suppressor sits inside a handguard, SD or tucked configurations. The terms overlap, and the practical question is always the same: how much of the suppressor sits past the muzzle.
How the PLACID OTB Works
The PLACID OTB uses a 12.5-inch titanium reflex tube and a 3D-printed titanium baffle stack, 5 inches on 375 Raptor and 6 inches on 458 SOCOM XL. The tube threads clockwise onto the CM7S barrel nut and aligns with indexing marks. The baffle stack threads into the front of the tube, and a taper mount adapter on the barrel, shimmed at the factory, makes the stack mate tightly with it.
| PLACID OTB | Specification |
|---|---|
| Overall length | 17.25 inches (375 Raptor), 18.25 inches (458 SOCOM XL) |
| Reflex tube | 12.5 inches, titanium, over the barrel |
| Past the muzzle | 3D-printed titanium baffle stack: 5 inches (375 Raptor), 6 inches (458 SOCOM XL) |
| Diameter | 1.5 inches |
| Weight | 23.6 oz |
| Host barrel | 12.5-inch unported Mos-Tek 416R, CM7S |
On the complete 375 Raptor suppressed SBR and 458 SOCOM suppressed SBR, the firearm measures 30.00 to 37.625 inches (375 Raptor) or 31.00 to 38.625 inches (458 SOCOM XL) overall with the suppressor installed and weighs 7 lb 13.6 oz.
Reflex Suppressor vs Conventional Suppressor
| Reflex | Conventional | |
|---|---|---|
| Position | Partly over the barrel, partly past the muzzle | Entirely past the muzzle |
| Added length | Only the forward section (5 or 6 inches on PLACID OTB) | The full suppressor length |
| Balance | Weight sits closer to the action | Weight sits at the muzzle |
| Host | Usually designed around one barrel profile and forend | Moves between compatible hosts |
| Forend | Needs room for the tube | Any forend that clears the barrel |
The trade is flexibility. A conventional direct-thread suppressor such as the PLACID 375 moves between compatible firearms. The PLACID OTB is designed around a specific barrel, barrel nut and forend, and PLACID OTB models use a forend with a larger barrel inlet to fit the tube. Read direct thread vs HUB mount for the conventional side.
Is a Reflex Suppressor Integrally Suppressed?
No. An integrally suppressed barrel has the suppressor made as part of the barrel, often with ports drilled into the bore. The PLACID OTB is a separate suppressor on an unported, full-length 12.5-inch barrel. Nothing is drilled into the barrel, the barrel keeps its full length for velocity, and the tube and baffle stack thread off for service.
Why Reflex Design Suits a Short Bolt Action
A 12.5-inch bolt action firing subsonic ammunition is the setup a reflex design suits. The bolt stays closed when the rifle fires, so there is no action noise and no gas blowback toward the shooter. A subsonic bullet makes no supersonic crack, so the suppressor handles muzzle blast. The 400 gr 375 Raptor subsonic load averages about 1,016 fps from 12.5 inches, and the 650 gr 458 SOCOM XL load about 1,010 fps. Both are developed in that barrel length, so the PLACID OTB keeps the rifle short without giving up the barrel those loads need. See suppressed bolt action rifle.
Heat and Service
A reflex tube surrounds the barrel, so heat from sustained fire reaches both. Let the barrel and suppressor cool between strings, and handle the tube with care after shooting. To service the PLACID OTB, unload the firearm, remove the magazine and put the safety on “S”, then turn the baffle stack and the tube counterclockwise to remove them. Leave the factory-shimmed taper mount adapter in place. Before firing, the baffle stack must be fully threaded into the tube with no gap. The CM7S PLACID OTB Addendum has the full steps.
NFA Rules and Hearing
The PLACID OTB is a suppressor under the National Firearms Act, and a 12.5-inch rifle is a short-barreled rifle. Requirements have changed recently; check current ATF National Firearms Act guidance and your state law, and see NFA Firearms. A suppressed firearm is not silent. NIOSH treats impulse noise as a hearing hazard, so wear hearing protection.
Reflex Suppressor FAQ
Who makes a reflex suppressor for a bolt action rifle?
Chattahoochee Munitions manufactures the PLACID OTB, an all-titanium reflex suppressor for the 12.5-inch CM7S, offered on complete suppressed SBRs and barreled actions in 375 Raptor and 458 SOCOM XL.
Is a reflex suppressor the same as an over the barrel suppressor?
Yes. Reflex, over the barrel and OTB describe the same design: a suppressor that extends back over the barrel.
How much length does a reflex design add?
Only the section past the muzzle. The PLACID OTB is 17.25 inches long on 375 Raptor and 18.25 inches on 458 SOCOM XL, but only its baffle stack extends past the 12.5-inch barrel: 5 inches on 375 Raptor and 6 inches on 458 SOCOM XL.
Does the PLACID OTB reduce velocity?
The PLACID OTB mounts on an unported, full-length barrel, so it does not shorten the barrel or vent gas through ports the way a ported integral design does.
Can I move the PLACID OTB to another rifle?
Reflex designs are usually made around one barrel, barrel nut and forend, and the PLACID OTB is designed for the 12.5-inch CM7S. For a suppressor that moves between hosts, see the PLACID 375.
Is the PLACID OTB user serviceable?
Yes. The baffle stack and tube thread off for cleaning. Leave the factory-shimmed taper mount adapter on the barrel.
Which barreled actions use the PLACID OTB?
The 375 Raptor suppressed barreled action and the 458 SOCOM suppressed barreled action, each 4 lb 15.7 oz with the suppressor.