//Understanding Suppressor Mounting
PLAN B MOUNT
Field Answers No. 02 — Installing and Using the Plan B Hub and Suppressor Mount
Two tapers, no latches, no timing. Clean it, seat it, check it.
// The Short Answer
Fit the muzzle device to the barrel. Fit the hub mount to the suppressor. Verify alignment. Then thread the suppressor on until the tapers seat.
A Plan B system is two parts and two matching tapers. A Plan B-pattern muzzle device goes on the barrel, and the Plan B hub mount threads into the back of the suppressor. When the suppressor is screwed onto the muzzle device, the tapers meet, and that contact is what holds and aligns it. There is no latch, no ratchet and no locking collar. That simplicity is the reason to choose the system, and it is also the reason the system asks two things of the owner: keep the tapers clean, and check that the suppressor is still tight.
// Before You Touch It
Clear the firearm. Every time.
Remove the magazine, lock the action open, and confirm the chamber is empty by eye and by finger before installing, mounting, removing or checking anything at the muzzle — including a tightness check between strings. A suppressor that has been fired is hot enough to burn. Let it cool or use a heat-resistant glove or mitt. Never look down the bore from the muzzle end to judge alignment; use a rod.
// Verify With Your Manufacturer
Our FAQs are designed to provide general advice. For specific manufacturers, we urge you to consult their specifications and details. Confirm every detail on this sheet with the manufacturer of the parts you are using. The torque figures, thread directions, thread locker guidance and compatibility notes here are published values and general practice, gathered for reference. Manufacturers differ from one another and they revise their instructions. Before you install or fire, check each detail against the current instructions for your specific muzzle device, mount and suppressor, or contact that manufacturer directly. Where this sheet and the manufacturer disagree, follow the manufacturer.
// Two Parts. Two Tapers. One Joint That Matters.
The taper does the holding and the aligning. The threads only pull it together.
On a flat-shouldered direct-thread mount, the suppressor squares itself against a narrow shoulder. On a taper mount, a cone on the muzzle device seats inside a matching cone in the hub mount. That gives more contact area, centers the suppressor as it tightens, and closes off the threads behind it from most of the carbon.
There are three threaded joints in the finished system, and they are not equal. The muzzle device stays on the barrel. The hub mount stays in the suppressor. The only joint you make and break in use is the one between them. The two permanent joints are torqued once and left alone; the working joint is tightened to a lower figure every time the suppressor goes on.
One point before the table. There is no single torque standard for this pattern. Several manufacturers make Plan B-pattern muzzle devices and their published figures differ. Where this sheet gives a range, the instructions packed with your parts are the controlling numbers. Read the card in the box before you reach for the wrench.
| The system | Specification |
|---|---|
| Parts | Plan B-pattern muzzle device on the barrel + Plan B hub mount in the suppressor |
| Retention | Matched tapers only — no latch, spring, collar or secondary lock |
| Hub thread | 1.375 x 24 into the suppressor (hub version) |
| Muzzle device to barrel | Per the muzzle device maker. Published figures run roughly 15 to 30 ft-lb |
| Hub mount to suppressor | Approx. 35 ft-lb — defer to your suppressor manual |
| Suppressor to muzzle device | Published figures run 10 to 15 ft-lb, on the mount’s wrench flats. No thread locker |
| Thread locker | Rocksett on the barrel threads |
| Anti-seize | High-temp anti-seize grease on the suppressor-to-muzzle-device threads |
| Shims, washers, timing | None required |
| Sizes | Standard and XL patterns do not interchange |
| Alignment | Rod check before the first round — see Q 08 |
| What it is not | Not a latching quick-detach — see Q 14 |
// Grease The Threads
Use a high-temperature anti-seize grease on the suppressor-to-muzzle-device threads. Heat and carbon can lock a suppressor joint solid, or gall it: the metal surfaces tear as they seize, damaging the threads on both parts. A thin film of an anti-seize grease made for suppressor threads, such as Breakthrough Clean Technologies Anti-Seize Gun Grease, which its maker rates to 1,800°F, keeps the joint coming apart cleanly. Apply it to the threads of the muzzle device and hub mount, wipe off the excess, and keep it out of the bore and off the baffles. Whether it also goes on the taper is your suppressor maker’s call. Leave the muzzle-device-to-barrel joint dry for its Rocksett. It is not a thread locker. Grease also lets a joint reach the same tightness at less torque, so do not add torque to make up for it. Follow your suppressor maker’s guidance where it differs.
// Watch It Done
// Questions We Get Asked
What is the sequence, start to finish?
Five stages. The first three are done once; the last two are done every time the suppressor goes on.
- Clear the firearm. Magazine out, action open, chamber checked by eye and by finger.
- Install the muzzle device on the barrel. Degreased threads, Rocksett, torqued to the maker’s figure. See Q 04.
- Install the hub mount in the suppressor. Clean threads, torqued firmly. See Q 05.
- Verify alignment with a rod. Before the first round, and again after any change at the muzzle. See Q 08.
- Mount, seat and re-check. Clean tapers, thread on until they meet, tighten, then check again after the first few rounds. See Q 09 and Q 10.
How do I know my parts match?
Check three things before anything is torqued. The muzzle device must be Plan B-pattern and the same size as the hub mount; standard and XL do not interchange. The muzzle device and the suppressor must both be rated for the caliber you are firing. And the muzzle device must seat correctly on your barrel’s shoulder, per its maker’s requirements. If any of the three is in doubt, stop and ask.
Do I need shims, a crush washer, or to time anything?
No. The system is designed to be installed without shims, washers or timing, and adding a crush washer works against it: a crush washer does not compress evenly, and anything that tilts the muzzle device tilts the suppressor with it. Thread the muzzle device straight onto clean threads against the barrel shoulder.
How do I install the muzzle device on the barrel?
With the firearm clear and the barrel or upper held in a proper fixture, not by the receiver in a bare vise:
- Degrease the muzzle threads, the barrel shoulder and the muzzle device threads.
- Apply Rocksett to the barrel threads. No crush washer, no shims. One maker notes it is not needed on a barrel with a tapered shoulder; follow the instructions for your muzzle device.
- Thread on by hand until it seats against the shoulder.
- Torque to the muzzle device maker’s specification. Published figures vary by maker — for example roughly 15 to 25 ft-lb on one and 20 to 30 ft-lb on another. Use the socket or wrench the device is designed for.
- Let the Rocksett cure per its label before firing, typically 24 hours.
How do I install the hub mount in the suppressor?
This is done once per suppressor and then left alone.
- Remove the factory mount following your suppressor’s manual.
- Clean the suppressor’s hub threads (1.375 x 24) and the threads on the mount.
- Thread the Plan B mount in by hand until it seats.
- Torque to roughly 35 ft-lb using the tools supplied with your suppressor, deferring to the suppressor manual where it gives a figure.
Why is the hub mount torqued harder than the suppressor is tightened?
Because you want the working joint to be the one that lets go. When you unscrew the suppressor, the same turning force acts on both the taper joint and the hub threads. If the hub mount is the looser of the two, the mount stays on the muzzle device and the suppressor comes off without it. A firmly torqued hub mount makes sure the taper releases first.
Should I use thread locker on the hub mount?
Follow your suppressor manufacturer’s guidance. The mount is designed to hold on torque alone, and some suppressor makers do not want compound on their hub threads. If your mount has backed out more than once on clean, correctly torqued threads, ask the suppressor maker what they approve before adding anything.
How do I verify alignment, and when?
With a caliber-appropriate alignment rod, on a cleared firearm, before the first round is ever fired through the combination.
- Mount the suppressor as you would to shoot it, tapers seated.
- Run the rod down the bore from the chamber end until it passes through the suppressor.
- Read it at the end cap. The rod should sit centered in the exit aperture and should not touch a baffle at any point.
- If it is off-center or touching, do not fire. Remove the suppressor, clean both tapers, reseat and check again. If it is still off, stop and have it inspected.
- Repeat the check after any change to the muzzle device, and for each new host and suppressor pairing.
How tight do I make it when I mount the suppressor?
Wipe both tapers and the threads clean, thread the suppressor on clockwise until the tapers meet, then tighten it to the figure in your instructions. Makers’ published figures run from 10 to 15 ft-lb, applied on the wrench flats of the mount and never on the suppressor tube. Many owners tighten by hand only; that is below what the makers publish. Use no thread locker on this joint; use a thin film of high-temperature anti-seize grease on the threads instead. And keep the tapers clean: carbon or grit on the cone stops it seating, and a joint that is not seated will not stay tight.
How often should I check that it is still tight?
After the first few rounds, and then periodically through the session. Heat cycling can loosen a taper joint, and with no secondary lock the check is the safeguard. Clear the firearm, use a heat-resistant glove or mitt, and confirm the suppressor has not backed off. Make it a habit at the same points every time, such as each magazine change or each trip downrange.
The suppressor is stuck. How do I get it off?
Let it cool first. A hot taper grips harder, and carbon adds to it. Once cool, a firm, steady counter-clockwise turn usually releases it, by hand or with a wrench on the flats of the mount. Do not put a pipe wrench, strap wrench or vise on the suppressor body; tubes are not built for that load. If it will not release when cool, bring it to us or to a qualified gunsmith.
The hub mount stayed on the muzzle device. Now what?
It was under-torqued in the suppressor. Let everything cool, remove the mount from the muzzle device using its wrench flats or the tool designed for it, then clean the hub threads on both parts and reinstall the mount to the correct torque. See Q 05 and Q 06. Re-check alignment before firing again.
What are the advantages of a Plan B system?
The case for it comes down to alignment and simplicity.
- Repeatable alignment. Matched tapers give more contact area than a flat shoulder and center the suppressor as it tightens.
- Simple installation. No shims, washers, latches, springs or timing of the muzzle device.
- Thread protection. The taper seats ahead of the threads and keeps most fouling off them.
- Light and compact. The hub mount is a small part in heat-treated stainless, around 2 oz by its maker’s figure, and the system adds little length compared with latching mounts.
- Nothing to wear out. No moving parts means no springs, collars or ratchets to break or carbon up.
- Broad compatibility. The hub version fits suppressors with 1.375 x 24 threads, and several manufacturers make Plan B-pattern muzzle devices, so one suppressor can serve several hosts.
- Nothing to operate. There is no latch or collar to hold open or line up while the suppressor goes on or comes off.
What are the trade-offs?
Every one of them follows from the same design choice: the taper is the only thing doing the work.
- No secondary lock. Retention depends on the taper and on how well it was tightened. It can loosen under heat cycling and has to be checked. A hub locking mount adds one; see Field Answers No. 03.
- Not a true quick-detach. It takes several full turns to mount or remove, which is slower than a latching or coarse-thread system.
- Tapers can stick. Heat and carbon can seize the joint until it cools or is cleaned.
- The mount can unscrew from the suppressor. If the hub mount is under-torqued, it may stay on the muzzle device. See Q 12.
- The taper surfaces are critical. A ding, galling or debris on either cone compromises seating and alignment.
- Sizes and makers vary. Standard and XL do not interchange, and mixing manufacturers adds a tolerance question, so verify alignment for each combination.
- No single torque standard. Each manufacturer’s instructions have to be followed for its own parts.
What maintenance does it need?
Very little, but what there is matters, because the tapers are the mount.
- Brush carbon off the muzzle device taper and threads after each session, and wipe the cone inside the hub mount.
- Renew the anti-seize grease on the threads once they are clean, so carbon cannot lock or gall the joint.
- Inspect both taper surfaces for dings or galling. Damage there affects alignment; do not shoot on a damaged taper.
- If the hub mount backs out of the suppressor, clean both threads and re-torque it.
- Re-check alignment after any work at the muzzle.
// What This Mount Does Not Do
It aligns and holds a suppressor well. It does not check itself.
- It has no secondary lock. Nothing stops the suppressor backing off except a clean, seated taper and an owner who checks it. See Q 10.
- It is not a latching quick-detach. If speed of removal or a positive lock is the priority, that is a different mount. Most suppressor manufacturers now offer a hub locking mount; see Field Answers No. 03. For mounting with no muzzle device at all, see Field Answers No. 04 on direct thread. See also Q 14.
- It does not correct a barrel problem. A taper centers the suppressor on the muzzle device. It cannot fix muzzle threads that are not concentric with the bore, which is why the rod check comes first. See Q 08.
- It is not universal. Standard and XL patterns do not interchange, and bore size has to match the caliber. See Q 02.
- It does not replace cleaning. A fouled taper will not seat, and a taper that is not seated will not stay tight.
- This sheet is not your manual. Torque figures vary by maker, and the instructions supplied with your muzzle device, hub mount and suppressor are the controlling documents. Plan-B is a product name of Q, LLC; Second of Ten is not affiliated with Q. Other product names belong to their respective owners. Nothing here is legal advice regarding suppressor ownership or use.
// Keep A Record
Write down the combination you verified: the host, the muzzle device, the hub mount, the suppressor, the torque you used on each permanent joint, and the date the alignment rod passed clean. That gives you a known-good starting point to return to. If you move the suppressor to another host or change anything at the muzzle, it is a new combination and it gets its own rod check and its own line in the record.
// Where To Find Them
Second of Ten stocks a wide selection of mounting devices from various manufacturers. For more information or availability, visit our retail site, www.gundaddy.com, your one-stop source for all your firearms needs and accessories.
Clean tapers. Checked alignment. Then shoot.