"Over Tightening" is a Problem?

[mebgardner]

I do not understand why over tightening a thread interface on a can, can cause problems besides wrecking the threads.

I know nothing about over tightening when it comes to cans, and so I'm asking to be schooled. Searches for "over tightening" in this suppressor sub-forum did not reveal much.

I have in view three interfaces:
1) The HUB / ASR Bravo Adapter to Suppressor Rear Thread interface (and also the Alpha interface same location).
2a) Semi Auto, Tilting Barrel Handgun specific, I think: The Booster Rear to Spring Holder Thread interface.
2b) The Muzzle Device / adapter to HUB Adapter Thread interface.
3) The Muzzle Device / mount to Barrel Thread interface.

Each of these threaded interfaces may, or may not, have a torque spec. I can obtain a crows foot, or a socket, and a torque wrench for the correct size. (I likely have them already, and I know how to use them). Why should I bother paying attention to this detail? What else does it affect?

Torque application / re-torquing is frequently mentioned when the can has walked off or the interface is locked / frozen. However, I am mainly interested in initial, cold torque application to an interface, setting it up prior to first use. The other applications: Part comes loose during use, so grab the can cover and twist it back on application, or Crap Its Frozen Locked Now What? application, theres already plenty of that type of advise.

Torque application (when torquing to a spec value), changes when a compound is placed on the threads, but I can not find any mention of this aspect. It's widely understood in motorcycle and auto forums, usually offered when asking about things like spark plug tightening with or without anti-seize.

Should I ask the interface manufacturer for a torque spec value, if none is given in the documentation? I'm eyeing Rearden, Griffin and Dead Air, Plan A / Plan B and Xeno interfaces. I'm not focusing on the interface type here, I'm mainly interested in what I can learn from the community about threads, torque specs, and torque application leading to over tightening, how that might change with the addition of some kind of compound frequently mentioned (anti-seize, thread lockers, etc), and what the effects of over tightening are (besides the obvious duh "you stripped it").

 

[spife7980]

 

[375fan]

I have/use multiple cans, most are direct thread. In other words I screw them on till they stop turning, hand tight is all they need. Don't think you need to need to crank them hard.
I also have couple cans that are Saker ASR system, again they just need a gentle hand tightening,

 

[msgriff]

Muzzle device torque on the barrel threads can constrict the bore at the muzzle. How much constriction would depend on the torque value and the size of the threads in relation to the bore.

 

[ma smith]

Why would you overtorque threads on your barrel? You basically take metal past the 'stretch' into the 'deform' mode...

 

[chevy_man]

Hand tight is just right. If you need more than a snap of the wrist something else is wrong.

 

[FuhQ]

 

[FuhQ]

Hand tight is just right. If you need more than a snap of the wrist something else is wrong.

*** The above advice can be applied to multiple things in life. ***

 

[hafejd30]

 

[Cascade Hemi]

I do not understand why over tightening a thread interface on a can, can cause problems besides wrecking the threads.

I know nothing about over tightening when it comes to cans, and so I'm asking to be schooled. Searches for "over tightening" in this suppressor sub-forum did not reveal much.

I have in view three interfaces:
1) The HUB / ASR Bravo Adapter to Suppressor Rear Thread interface (and also the Alpha interface same location).
2a) Semi Auto, Tilting Barrel Handgun specific, I think: The Booster Rear to Spring Holder Thread interface.
2b) The Muzzle Device / adapter to HUB Adapter Thread interface.
3) The Muzzle Device / mount to Barrel Thread interface.

Each of these threaded interfaces may, or may not, have a torque spec. I can obtain a crows foot, or a socket, and a torque wrench for the correct size. (I likely have them already, and I know how to use them). Why should I bother paying attention to this detail? What else does it affect?

Torque application / re-torquing is frequently mentioned when the can has walked off or the interface is locked / frozen. However, I am mainly interested in initial, cold torque application to an interface, setting it up prior to first use. The other applications: Part comes loose during use, so grab the can cover and twist it back on application, or Crap Its Frozen Locked Now What? application, theres already plenty of that type of advise.

Torque application (when torquing to a spec value), changes when a compound is placed on the threads, but I can not find any mention of this aspect. It's widely understood in motorcycle and auto forums, usually offered when asking about things like spark plug tightening with or without anti-seize.

Should I ask the interface manufacturer for a torque spec value, if none is given in the documentation? I'm eyeing Rearden, Griffin and Dead Air, Plan A / Plan B and Xeno interfaces. I'm not focusing on the interface type here, I'm mainly interested in what I can learn from the community about threads, torque specs, and torque application leading to over tightening, how that might change with the addition of some kind of compound frequently mentioned (anti-seize, thread lockers, etc), and what the effects of over tightening are (besides the obvious duh "you stripped it").

If you know how to use a torque wrench and understand fastener torque specifications, why did you start this thread?

 

[Charmingmander]

How hard is it to follow instructions from the manufacturer?

I swear some of the most retarded fucking questions that come up around guns would be answered if you read the fucking instructions.

 

[tsavo303]

How hard do you make it to brush your teeth?
do you use a protractor to check brush angle?
do you test the viscosity of the toothpaste every day? Is the abrasive content within spec?
is your water the correct ph every time?
Is your bathroom fan causing winds that affect your brushing technique?

 

[mebgardner]

If you know how to use a torque wrench and understand fastener torque specifications, why did you start this thread?

OK, Fair Question. I recognize you as an expert on this forum, and that I'm no longer seen as deserving of humor, but I'm being a PITA. Let me try to answer your question to redeem myself.

It's these specific fasteners (the stacked threaded interfaces), being used in this manner (multiple different parts inline and maintain a straight path while applying locking force), that I dont know anything about.

I have two of these HUB cans inbound. I'm having a 3rd out being converted to the interface by ECCO.

On the TBAC HUB compatible cans website pages, there is this disclaimer: "The HUB interface version of this suppressor is meant for advanced users who are familiar with HUB-compatible mounts and know how to use their choice of HUB mounting system in a secure, reliable, and repeatable manner. If you get the HUB version, you should know what you're doing. Everything behind the suppressor body is your responsibility."

I *dont* yet know what I'm doing with the application of torque force for these parts. I'm not assuming anything about the fasteners (the threaded interfaces). I can not find not much guidance offered in the archives, either.

On cans I purchased previously, I was lucky if I got a torque spec on the *one* DT interface the can had in the back. That there are now possibly *three* of them, and that they may be / could be from different manufacturers, each giving an opportunity to walk loose, makes the potential for mistakes much higher.

I also read a few threads in this archive that stated that it was possible to over torque an interface and cause problems more than just wrecking the part. Accuracy or precision problems were mentioned. But, they did not give the configuration of the host platform, or the can interface stack up (more than one interface? which one?)

I'm ignorant, and decided to ask some questions.

So, Sir. Respectfully, Would you please impart to me what tips and advice you have to offer?

If I gave an interface stack up of what I believe is a popular configuration, please tell me how I should proceed to torque things down for an initial shoot.

A .30 cal HUB suppressor rear to a 5/8"x24 threaded barrel, with a QD muzzle device in between. Lets say the barrel has wide enough and suitable indexing shoulder past the threads. (ie: no indexing on the muzzle). May or may not use a crush or peel washer, depending on the muzzle device selected (MB may need timing, maybe not). Lets say 17-4 steel for all components with high quality class 3 threads on each one. But, I dont know if using 4140 nitrided makes a change to anything or if Titanium might also change methods. I will use the FH / MB interface to unlock and move the can around to different platforms. I think just that one interface (2) will remain non-permanent.

Would look like this:
(1) 1.375x24 HUB to can rear interface.
(2) 0.900"x24 FH / MB to HUB interface.
(3) 5/8"x24 FH/MB to Barrel interface.

I have experience with torquing and timing many AR barrel nuts using a reaction bar, and I've also mounting many barrel FHs and MBs, some with flats and some not. I have some small experience to draw on for "feel". I also am familiar with that "Oh Shit, I've gone and Done It Now." feeling.

I think I could possibly do alot of damage using just simple hand tools, like a strap wrench. New lightweight designs could warp or deform at one or more interfaces if I did this wrong? I just dont know. One DT interface is easy, sure. The TBAC disclaimer put me on notice to proceed carefully. This is me wading in slowly, carefully.

You probably can not advise me on actual torque values, thats OK. I'm requesting advice and tips for methods, "which one first" if ordering is important, and potential dangers to watch for ("its easy to screw up here").

Thanks for the help.

 

[ma smith]

5/8-24 is an obscure thread pitch, originally used for aviation spark plugs
the nominal (dry) torque spec for 5/8-24 is ~35 ft lbs.

wet, or coated parts, you need to lower your torque, typically 20-30%,
read manuals ect on surface treatments/anti-seize etc you are using.
some recommend as low as 25 ft lb, IIRC if its nitride and anti-seize etc.

maybe TBAC can give you better guidance, specific to the product...
In general, just follow OEM spec and/or absent any guidance, industry standards





(My $0.02 cents of advice)

 

[Cascade Hemi]

OK, Fair Question. I recognize you as an expert on this forum, and that I'm no longer seen as deserving of humor, but I'm being a PITA. Let me try to answer your question to redeem myself.

It's these specific fasteners (the stacked threaded interfaces), being used in this manner (multiple different parts inline and maintain a straight path while applying locking force), that I dont know anything about.

I have two of these HUB cans inbound. I'm having a 3rd out being converted to the interface by ECCO.

On the TBAC HUB compatible cans website pages, there is this disclaimer: "The HUB interface version of this suppressor is meant for advanced users who are familiar with HUB-compatible mounts and know how to use their choice of HUB mounting system in a secure, reliable, and repeatable manner. If you get the HUB version, you should know what you're doing. Everything behind the suppressor body is your responsibility."

I *dont* yet know what I'm doing with the application of torque force for these parts. I'm not assuming anything about the fasteners (the threaded interfaces). I can not find not much guidance offered in the archives, either.

On cans I purchased previously, I was lucky if I got a torque spec on the *one* DT interface the can had in the back. That there are now possibly *three* of them, and that they may be / could be from different manufacturers, each giving an opportunity to walk loose, makes the potential for mistakes much higher.

I also read a few threads in this archive that stated that it was possible to over torque an interface and cause problems more than just wrecking the part. Accuracy or precision problems were mentioned. But, they did not give the configuration of the host platform, or the can interface stack up (more than one interface? which one?)

I'm ignorant, and decided to ask some questions.

So, Sir. Respectfully, Would you please impart to me what tips and advice you have to offer?

If I gave an interface stack up of what I believe is a popular configuration, please tell me how I should proceed to torque things down for an initial shoot.

A .30 cal HUB suppressor rear to a 5/8"x24 threaded barrel, with a QD muzzle device in between. Lets say the barrel has wide enough and suitable indexing shoulder past the threads. (ie: no indexing on the muzzle). May or may not use a crush or peel washer, depending on the muzzle device selected (MB may need timing, maybe not). Lets say 17-4 steel for all components with high quality class 3 threads on each one. But, I dont know if using 4140 nitrided makes a change to anything or if Titanium might also change methods. I will use the FH / MB interface to unlock and move the can around to different platforms. I think just that one interface (2) will remain non-permanent.

Would look like this:
(1) 1.375x24 HUB to can rear interface.
(2) 0.900"x24 FH / MB to HUB interface.
(3) 5/8"x24 FH/MB to Barrel interface.

I have experience with torquing and timing many AR barrel nuts using a reaction bar, and I've also mounting many barrel FHs and MBs, some with flats and some not. I have some small experience to draw on for "feel". I also am familiar with that "Oh Shit, I've gone and Done It Now." feeling.

I think I could possibly do alot of damage using just simple hand tools, like a strap wrench. New lightweight designs could warp or deform at one or more interfaces if I did this wrong? I just dont know. One DT interface is easy, sure. The TBAC disclaimer put me on notice to proceed carefully. This is me wading in slowly, carefully.

You probably can not advise me on actual torque values, thats OK. I'm requesting advice and tips for methods, "which one first" if ordering is important, and potential dangers to watch for ("its easy to screw up here").

Thanks for the help.

Most muzzle device manufacturers recommend tightening 5/8-24 to around 30lbft to 35lbft. TBAC recommends gluing their muzzle devices on though.

As for the HUB mount, that torque spec is probably 150ftlb+ for an unhardened fastener. A 1"-14 fine pitch, grade 2, calls out above 180lbft for example. There are tons of stories about HUB mounts spinning out of silencers. TBAC probably doesn't recommend that much torque though.

Probably call TBAC, they intentionally disclaimed HUB because it is a dumpster fire for even advanced users.

 

[mebgardner]

That's really useful info, fellows. Thanks very much.

I had not read well enough about the problems with a can's HUB interface spinning out of its mount. I will take that as one of those "be careful here" points.

Those 150 - 180 ft-lbs values are near identical to the value for an M4 extension into an AR barrel. Those are big numbers. One of my whoops moments was unlocking an M4 extension from a barrel. That was an expensive day, and I recall that big torque feeling well.

Thanks for the leg up.

 

[Cascade Hemi]

That's really useful info, fellows. Thanks very much.

I had not read well enough about the problems with a can's HUB interface spinning out of its mount. I will take that as one of those "be careful here" points.

Those 150 - 180 ft-lbs values are near identical to the value for an M4 extension into an AR barrel. Those are big numbers. One of my whoops moments was unlocking an M4 extension from a barrel. That was an expensive day, and I recall that big torque feeling well.

Thanks for the leg up.

Use a barrel vice to install and remove muzzle brakes/FHs.

 

[mebgardner]

Use a barrel vice to install and remove muzzle brakes/FHs.

Whose vise do you like? I don't have one yet. I have a large steel jaw vise bolted to my bench, so if it fits into one of those, that would be good to know. I've been using blocks of red oak with the barrel sandwiched between them, for non AR barrel vise operations. Not optimum, but it got me by the couple times I needed to do it. For AR, I've been using a reaction rod, a good one.

On tools, do you have a suppressor alignment gauge vendor that you prefer? I need one or two of those too, to finish check for no baffle strike alignments.

(Edit: Geissele sells these SAG rods, but they are pricey new, at $75 to $125 each).

 

[Cascade Hemi]

I have a Viper barrel vice as well as a homemade barrel vice I made from angle iron and lead. If your barrel is slipping in the wood try some thin leather or drywall joint paper.

You can visually inspect alignment from the breach.

 

[Arc Light]

I've used 25-30 Lb-ft on all my muzzle devices and HUB mounts without either ever coming loose. The key is that I use high-temp red thread-locker, as per TBAC's recommendations. A lot of people seem hesitant to use red thread-locker in this application, and I'm not sure why. I've removed every one that I needed to by applying heat from a propane torch for 30 seconds to heat up the joint first. They then come apart easy with no drama. I agree on using a barrel vice when installing or removing muzzle devices. I've used the Davidson's barrel vice that I bought on eBay for around $80 and it has never failed me. One thing I did was add two strips of leather between the barrel and the vice, and it has never spun on me.

 

[mebgardner]

5/8-24 is an obscure thread pitch, originally used for aviation spark plugs
the nominal (dry) torque spec for 5/8-24 is ~35 ft lbs.

wet, or coated parts, you need to lower your torque, typically 20-30%,
read manuals ect on surface treatments/anti-seize etc you are using.
some recommend as low as 25 ft lb, IIRC if its nitride and anti-seize etc.

maybe TBAC can give you better guidance, specific to the product...
In general, just follow OEM spec and/or absent any guidance, industry standards





(My $0.02 cents of advice)

5/8"x24 is an arcane thread pitch, huh? Not common use. I did not know that about it's aircraft spark plug related origion.

Thanks for the percentage amounts suggestions for backing off torque values for wet or coated parts, that's handy to know.

Would you include anerobic thread lockers in that list of wet compounds? Yes, they begin as liquid, so I'm just confirming what I think the answer is: Yes.

 

[Arc Light]

I personally don't reduce torque when using thread lockers on threads this large, but I do when using any kind of oil or grease. I'm OCD about this kind of stuff and research the hell out of it. Curiously, Permatex, one of the largest makers of thread lockers does not recommend any reduction in torque when using one of their products. Yet Henkels, makers of Loctite, does recommend a torque reduction (10-20% if I recall). Either way, we're only talking a few pound-feet difference, not enough to worry about imho.

 

[mebgardner]

I personally don't reduce torque when using thread lockers on threads this large, but I do when using any kind of oil or grease. I'm OCD about this kind of stuff and research the hell out of it. Curiously, Permatex, one of the largest makers of thread lockers does not recommend any reduction in torque when using one of their products. Yet Henkels, makers of Loctite, does recommend a torque reduction (10-20% if I recall). Either way, we're only talking a few pound-feet difference, not enough to worry about imho.

That is curious about the Permatex .vs Henkels recommendation differences. Is the Permatex recommendation of no reduction, a recommendation by silence? Or, do they come out and state that?

 

[Arc Light]

That is curious about the Permatex .vs Henkels recommendation differences. Is the Permatex recommendation of no reduction, a recommendation by silence? Or, do they come out and state that?

They state it on their packaging and also in their Technical Data Sheets. From their red threadlocker TDS:

"Assemble and tighten as usual. When tightening to
established torque values, torque compensation is not
required"

 

[Supersubes]

Why would you overtorque threads on your barrel? You basically take metal past the 'stretch' into the 'deform' mode...

This happens a lot. Brake indexes a little short, add a little torque to get it plumb. Then notice their accuracy went to shit.

 

[Supersubes]

Whose vise do you like? I don't have one yet. I have a large steel jaw vise bolted to my bench, so if it fits into one of those, that would be good to know. I've been using blocks of red oak with the barrel sandwiched between them, for non AR barrel vise operations. Not optimum, but it got me by the couple times I needed to do it. For AR, I've been using a reaction rod, a good one.

On tools, do you have a bore guide rod (I don't know what it's called) vendor that you prefer? I need one or two of those too, to finish check for no baffle strike alignments.

You can buy rubber from mcmaster to creat soft jaws for your vice. Clamp the can horizontally to spread the load.

If youre installing/removing the can by hand, there’s no need to go crazy on the can side adapter torque. Area 419 hellfire system uses a left handed thread between the can adapter and the muzzle device. So you unscrew the can by turning it clockwise. So while removing the can, youre also tightening the muzzle device to the muzzle, and the can adapter to the can.

 

[mebgardner]

I've got the gist of the operations now, gentlemen.

Torque and time the muzzle device interface to barrel (3) (use a barrel vise). Torque HUB interface to suppressor rear (1). Torque QD adapter to HUB adapter (2). For my app, (3) and (1) will be permanently locked, so select and use a locking compound. Also for those interfaces, work up to the final torque value, 2 maybe 3 passes. (Not discussed, but I think it would be appropriate). Use manufacturer recommended torque spec if available, otherwise there are some "Kentucky windage" values given here that are likely appropriate, and could be used. Derate final torque value for wet or coated parts as deemed appropriate.

Once done, use a professional Suppressor Alignment Gauge, like a Geissele SAG, to check confirm a centered ballistic path thru barrel, parts and can.

I had considered moving cans around based on the HUB interface, selecting different adaptors (trying to save money by deleting the QD interface). But, I will verify that 150-180 ft lbs value range with a couple of interface parts vendors. That was an unexpected nugget of knowledge, but the number is scary big (to me). If it's for real, and I have no reason to doubt it, then I for sure don't want to unlock interface (1) unless absolutely necessary. Better to buy and use a QD for (2) than to risk unlocking that (1).

Thank you folks for the help.

 

[mebgardner]

This happens a lot. Brake indexes a little short, add a little torque to get it plumb. Then notice their accuracy went to shit.

This. This is what I remember reading in a few places. It was torque related, and caught my attention.

How do you fix it?

 

[DangerRanger]

I think you’re over worried about it. Just don’t go full gorilla on it.

I know people talk about hand tight with direct thread but there’s an interesting bit in cgs manual here:

For normal use, very hand tight will do. For extended use, torque the Hyperion using the 7/8” wrench flats to the barrel threads to 25-30ft/lbs while using an armorers tool such as the Geissele Reaction Rod (if needed) to prevent tweaking or damage to the host firearm gas system or barrel assembly.

For me most of my cans are griffin qd taper mount and I just get the brakes a bit past hand tight but nothing nuts and haven’t had an issue. I crank my can on by hand pretty hard but nothing nuts, haven’t had an issue with them in use.

 

[Supersubes]

This. This is what I remember reading in a few places. It was torque related, and caught my attention.

How do you fix it?

Use less torque, and use a thread locker. Easy peasy.

Any talk about spec toque based on thread size isn't applicable here imo.

 

[mebgardner]

Any talk about spec toque based on thread size isn't applicable here imo.

I'm interested in the "why" of this statement, but at this point, I'm concerned about community reaction to my tendency to bloat out topics. It was pretty ugly on this one at first.

Maybe it would be best to just point me at something to read, and I will go read it.

 

[Supersubes]

I'm interested in the "why" of this statement, but at this point, I'm concerned about community reaction to my tendency to bloat out topics. It was pretty ugly on this one at first.

Maybe it would be best to just point me at something to read, and I will go read it.

If you're looking for exact numbers, you're not going to find them easily. The parts being screwed together aren't just nuts and bolts. Fortunately it doesn't matter much, especially in the area of suppressors.

 

[SDet]

I'm interested in the "why" of this statement, but at this point, I'm concerned about community reaction to my tendency to bloat out topics. It was pretty ugly on this one at first.

Maybe it would be best to just point me at something to read, and I will go read it.

Book specs based on thread size are based on solid bolts and spec size nuts.

We're dealing with thin body parts with a thin wall nut. We're also typically dealing with dissimilar metals and coatings, quite different than dry steel that the sae specs are based around.

 

[mebgardner]

I've used 25-30 Lb-ft on all my muzzle devices and HUB mounts without either ever coming loose. The key is that I use high-temp red thread-locker, as per TBAC's recommendations. A lot of people seem hesitant to use red thread-locker in this application, and I'm not sure why. I've removed every one that I needed to by applying heat from a propane torch for 30 seconds to heat up the joint first. They then come apart easy with no drama. I agree on using a barrel vice when installing or removing muzzle devices. I've used the Davidson's barrel vice that I bought on eBay for around $80 and it has never failed me. One thing I did was add two strips of leather between the barrel and the vice, and it has never spun on me.

I will not be able to use the red thread locker for every app.

The MB to Barrel (3) interface for a handgun barrel, that needs to be removed for a field strip cleaning. It's the piston to barrel interface.

It's not a problem, I was reminded of it while considering what should be "permanently" locked.

The torque values are not problematic here, either. The barrel will get cocked sideways in the slide, probably with most of the twisting force into the ejection port area. I think they are low enough to not cause any damage to the barrel external chamber or the slide. Kinda depends on the locker compound chosen. Not Red.

I also realized that I started talking about a continuing use case, instead of a first use case. So, I must be finished. Thanks guys, I'm out.

 

[mebgardner]

I am following up on some content in this thread that had substantial differences in torque numbers.

I obtained torque numbers for the (1), suppressor to HUB thread interface from a couple of respected can manufacturers, and I will include them as content for this thread so the info can be easily found in the future.

TBAC (Zak) publishes:
Do not exceed 40 ftlbs
Loctite is your call.

Otter Creek Labs publishes for their DT adapter:
Use a high temp thread locker such as Rocksett or Red Loctite, on both the DT adapter HUB and barrel threads.
Use a wrench to torque to 25-30 ftlbs, on both the DT adapter HUB and barrel threads. (So, "wet" torque numbers).

If I get any further information from ECCO, I will edit this note.

 

[hlee]

I have one suppressor that will shoot loose from its mount if only hand tight. I use a torque wrench to tighten it to 20 Ft lbs. That is tighter than I can get it by hand, but the torque wrench doesn’t allow me to go full ham on it. Why 20 ft lbs? It is the min setting on the wrench…

 

[mebgardner]

I will add one further note about alignment checking. I believe it is a builders mistake to not use tools to perform an alignment check after an initial build up, or stack up, of these multiple interfaces (1 thru 3). I would advise to use an alignment gage tool even if all your were building was a single DT interface. Said a different way, IMO looking down the barrel, breech to muzzle, is a not good enough check. Yes, the manufacturers now provide these magnificently made products, finely cut metals with machine controlled and ultra sharp tools to exacting specs. Just Roll With It.

No. I guess I'm just an old guy looking for a good excuse to buy good tools. I like Geissele's "Minute of Eyeball" as the spec for a successful test pass result (found within their user manual for their suppressor alignment gage, SAG tool). Huxwrx also makes a set of very good gages made from carbon fiber. They're cheaper than the steel tools, too.

 

[mebgardner]

I have one suppressor that will shoot loose from its mount if only hand tight. I use a torque wrench to tighten it to 20 Ft lbs. That is tighter than I can get it by hand, but the torque wrench doesn’t allow me to go full ham on it. Why 20 ft lbs? It is the min setting on the wrench…

We're still talking about torque application and possible over torque, so still on topic for those watching. I took heat for this previously, and the heat was justified. That was my fault, my mistake, so I'm paying attention to it.

Mechanical torque wrenches are not accurate at the limits of their range. Their accuracy gets worse the closer you get to a limit at either end of the range. The "click", or number shown on the dial, may not be too close to the number you want to achieve. I dont know about the electronic strain gage variety, and I have no opinion on them. I guess my .02 is to buy a bigger wrench.

My own experience is torque wrenches are really difficult to manage well while using them. They seem simple enough, but if you make the parts slippery with specialty coatings, or thread locking compounds, then the game changes. While torquing, those threads continue to sliiiiiiiiide and I just dont seem to be getting any closer to the torque number I want. It starts to feel like Im approaching thread deformation (or fastener snapping) range, but the indicator says I have a ways to go to get to the final number I want. Like most learning, it comes with experience and sometimes breaking a few. But, an old hand to demonstrate is also very valuable. Watch a gunsmith if you get an opportunity. I teach my neighbors to build.

The numbers in this thread are not in those extreme ranges. The 20 - 40 ftlb are well outside the thread deformation range for any of the interfaces, for these metals, wet, dry or coated, for these sizes of parts. Nothing to worry about.

Buy and use good quality tools, and try to put the torque number you want near the middle of it's range.

 

[Cascade Hemi]

I will add one further note about alignment checking. I believe it is a builders mistake to not use tools to perform an alignment check after an initial build up, or stack up, of these multiple interfaces (1 thru 3). I would advise to use an alignment gage tool even if all your were building was a single DT interface. Said a different way, IMO looking down the barrel, breech to muzzle, is a not good enough check. Yes, the manufacturers now provide these magnificently made products, finely cut metals with machine controlled and ultra sharp tools to exacting specs. Just Roll With It.

No. I guess I'm just an old guy looking for a good excuse to buy good tools. I like Geissele's "Minute of Eyeball" as the spec for a successful test pass result (found within their user manual for their suppressor alignment gage, SAG tool). Huxwrx also makes a set of very good gages made from carbon fiber. They're cheaper than the steel tools, too.

Says the new guy. Misaligned silencers are almost always obvious from the breach by eye. The silencer literally occludes the bore. The bore will center your eye like a bullseye and a misaligned silencer will look like a crescent moon. Not all bore strikes are caused by misalignment though so your alignment rod won't stop instable projectiles, or loose silencer components, from destroying you silencer.

 

[hlee]

Mechanical torque wrenches are not accurate at the limits of their range. Their accuracy gets worse the closer you get to a limit at either end of the range. The "click", or number shown on the dial, may not be too close to the number you want to achieve.

I think you missed the point. The only reason I use a torque wrench (TW) is that it gives me some mechanical advantage, with the addition of a “limiter.” I don’t really care about the actual torque. Set at the minimum value on the TW, I get more torque than without it, but less than I could apply with a breaker bar…

 

[308pirate]

My own experience is torque wrenches are really difficult to manage well while using them. They seem simple enough, but if you make the parts slippery with specialty coatings, or thread locking compounds, then the game changes. While torquing, those threads continue to sliiiiiiiiide and I just dont seem to be getting any closer to the torque number I want. It starts to feel like Im approaching thread deformation (or fastener snapping) range, but the indicator says I have a ways to go to get to the final number I want. Like most learning, it comes with experience and sometimes breaking a few. But, an old hand to demonstrate is also very valuable. Watch a gunsmith if you get an opportunity. I teach my neighbors to build.

This is what happens when one doesn't understand that torque is just a convenient analog for tensile stress on the fastener and doesn't understand the influence of fastener friction on the amount of tensile stress generated per degree of rotation.

 

[mebgardner]

Says the new guy. Misaligned silencers are almost always obvious from the breach by eye. The silencer literally occludes the bore. The bore will center your eye like a bullseye and a misaligned silencer will look like a crescent moon. Not all bore strikes are caused by misalignment though so your alignment rod won't stop instable projectiles, or loose silencer components, from destroying you silencer.

This is all true. I respect your advise and opinion. I am not singling you out, sir. I think we are both giving the best advice we can find. I am not intending to detract from your advice in the least.

From the Geissele User Manual, for their SAG tool:

"Suppressor alignment is determined by several factors:
1. Centerline alignment (offset and angular) of the barrel threads to the bore.
2. Perpendicularity of the barrel shoulder to the threads.
3. Alignment of the muzzle device’s internal diameter threads and torque shoulder to the suppressor attachment geometry.
4. Alignment of the suppressor mounting ID geometry to the bore of the suppressor."

"A small deviation at the mounting interface means a much larger deviation of the suppressor exit hole. The deviations from nominal can also be additive which compound suppressor misalignment."

So, there are many possibilities for misalignment to enter. We have 3 threaded interfaces in view, and possibly a 4th non threaded interface (the taper) all stacked up on top of each other.

I still advocate the use of tools as a good method to determine misalignment.

The converse might be true as well, and I wonder how often it happens? That the centricities stack up to cancel each other out? You "get lucky" that time, and then you take it apart... This made me consider what I will now do with handgun interfaces. When that (3) interface gets moved for gun cleaning, I will re-test using a SAG. Not a method I'm advocating for everyone here, just myself. I dont have the taper in view, and I'm not writing about the continuing operations of that either.

But, if I have two interfaces disturbed (the taper and (3), then I think I will re-check. I'm cleaning, so I'm likely at a bench and tools are likely nearby. Not field ops.

 

[mebgardner]

I think you missed the point. The only reason I use a torque wrench (TW) is that it gives me some mechanical advantage, with the addition of a “limiter.” I don’t really care about the actual torque. Set at the minimum value on the TW, I get more torque than without it, but less than I could apply with a breaker bar…

OK. Now I got it.

 

[mebgardner]

This is what happens when one doesn't understand that torque is just a convenient analog for tensile stress on the fastener and doesn't understand the influence of fastener friction on the amount of tensile stress generated per degree of rotation.

Yup! That, and I did not know when to stop, and no clue about what the fastener was telling me while doing it. Clueless.

But, I did learn and it happens less frequently these days.

 

[308pirate]

Yup! That, and I did not know when to stop, and no clue about what the fastener was telling me while doing it. Clueless.

But, I did learn and it happens less frequently these days.

You don't have to "listen" to the fastener if you actually know what you're doing. That's what I was trying to tell you.

The torque number you want in order to achieve the correct tensile stress (and thus clamping force) changes when the threads are lubricated. There are thumb rules out there for that, and if so inclined, you can learn how to calculate an offset.

 

[ma smith]

This is what happens when one doesn't understand that torque is just a convenient analog for tensile stress on the fastener and doesn't understand the influence of fastener friction on the amount of tensile stress generated per degree of rotation.

This is really important to grok...torque is a proxy variable, its not "the thing" we are interested in at the end of the day

 

[Cascade Hemi]

This is all true. I respect your advise and opinion. I am not singling you out, sir. I think we are both giving the best advice we can find. I am not intending to detract from your advice in the least.

From the Geissele User Manual, for their SAG tool:

"Suppressor alignment is determined by several factors:
1. Centerline alignment (offset and angular) of the barrel threads to the bore.
2. Perpendicularity of the barrel shoulder to the threads.
3. Alignment of the muzzle device’s internal diameter threads and torque shoulder to the suppressor attachment geometry.
4. Alignment of the suppressor mounting ID geometry to the bore of the suppressor."

"A small deviation at the mounting interface means a much larger deviation of the suppressor exit hole. The deviations from nominal can also be additive which compound suppressor misalignment."

So, there are many possibilities for misalignment to enter. We have 3 threaded interfaces in view, and possibly a 4th non threaded interface (the taper) all stacked up on top of each other.

I still advocate the use of tools as a good method to determine misalignment.

The converse might be true as well, and I wonder how often it happens? That the centricities stack up to cancel each other out? You "get lucky" that time, and then you take it apart... This made me consider what I will now do with handgun interfaces. When that (3) interface gets moved for gun cleaning, I will re-test using a SAG. Not a method I'm advocating for everyone here, just myself. I dont have the taper in view, and I'm not writing about the continuing operations of that either.

But, if I have two interfaces disturbed (the taper and (3), then I think I will re-check. I'm cleaning, so I'm likely at a bench and tools are likely nearby. Not field ops.

The consumer alignment rods you can buy will be no more accurate than your eye balls. Long before any company was selling "alignment rods" I was having rods custom ground for suppressor alignment. I eventually stopped because every application needed a custom grind to be accurate. The hand ground rod straightness would also change over time depending on how they were stored too. Feel free to do, or buy, whatever you want but you won't actually get what you think you are buying.

 

[mebgardner]

The consumer alignment rods you can buy will be no more accurate than your eye balls. Long before any company was selling "alignment rods" I was having rods custom ground for suppressor alignment. I eventually stopped because every application needed a custom grind to be accurate. The hand ground rod straightness would also change over time depending on how they were stored too. Feel free to do, or buy, whatever you want but you won't actually get what you think you are buying.

Oh. OK, thanks for the schooling. I was seeing this aspect from a new guy perspective, hoping that a gage tool would give the unschooled new guy (me) an advantage that I would not otherwise obtain from the old hand with the know-how, that I dont get access to at the build bench.

It's a good day. I learned something valuable. Thanks.

 

[carbonbased]

@308pirate told me blue locktite had the same effect on torque values as water. No effect.

Not sure about red locktite.

If you use red locktite, USE JUST A DAB.

You will thank me later.

And if you have a wife or roommates, apply it in the garage. That shit stinks.

 

[secondofangle2]

Muzzle device torque on the barrel threads can constrict the bore at the muzzle. How much constriction would depend on the torque value and the size of the threads in relation to the bore.

If the barrel has right hand twist, and so do the threads going from the other direction, tightening a muzzle device too much actually opens the bore which is bad for accuracy in centerfire rifles. So I am told. I am also told that the opposite is true for rimfire.

This has been an occasional topic of discussion and a problem that I have troubleshoot before. There is an old army manual about M14 rifles, saying that one should not screw on the muzzle device too tight or it can compromise accuracy

However, with thunder beast adapters, I have been told to absolutely slather it with 272 Loctite or else the can can seize upon the break and you will turn off your break when you try to remove the can with a strap wrench if it gets seized up. I know this because I had to send in my 338 ultra can, and not even thunder beast could get the break out of it so they had to machine it out on a lathe. I also now use high temperature anti-size on my thunder beast cans, so this doesn’t happen again