School me on muzzle threads

So I have been wondering this for a while. I understand the difference between threads, the fact that there are a certain amount of turns cut per inch etc. What I don’t know is what the different threads are used for? Can any thread be cut into any barrel? Are some threads used for specific barrels? I’m looking to cut down my .223, but also want to replace the current gunworks suppressor for a dpt. I have passed up on a few second hand supressors in the past because they were the wrong thread for the rifle. Can I buy another threaded suppressor and cut the barrel to suit?

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Originally Posted by Delphus

So I have been wondering this for a while. I understand the difference between threads, the fact that there are a certain amount of turns cut per inch etc. What I don’t know is what the different threads are used for? Can any thread be cut into any barrel? Are some threads used for specific barrels? I’m looking to cut down my .223, but also want to replace the current gunworks suppressor for a dpt. I have passed up on a few second hand supressors in the past because they were the wrong thread for the rifle. Can I buy another threaded suppressor and cut the barrel to suit?

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With my limited experience, most threads I see are 1/2" UNF but when you get up to about 30 cal a lot of them do 9/16ths . The reason for the size difference is the internal distance from the bottom/deepest part of the cut, is not much bigger than the bore

My usual advice is to get a thread cut by whoever makes your suppressor. While threads are supposed to be standardised there may be subtle variations in it that vary.

And may I ask why you want DPT over the Gunworks? On a 223 performance would be very similar in both I would have thought....

Cheers. Yeah performance between the two will be about the same, but the dpt has a fair bit less muzzle forward, and I want a shorter overall rifle. Dpt is also lighter by a fair bit.

The choice of threads is best selected according to the calibre so there is sufficient meat at the muzzle. The common sizes are: .22/223 - 1/2"x20 TPI (UNF) and 1/2"x28 (UNEF, AR15 etc). .243/6mm - same, .270/7mm - same or 9/16" UNF or 14x1mm, .30/7.62mm - 9/16"/14mm, .338" - 5/8" UNF or 16mm, and so on. The actual thread (Unified and Metric are both 60 degree vee) is of no consequence so long as it matches the suppressor. Aluminium suppressors are best with a coarser thread to avoid cross-threading.

A thread size has two measurements
- Major diameter
- Pitch

Attachment 164941

Pitch isn't that critical from my experience.

I do think major diameter is important though, choosing a suitable major diameter depends on:
- Barrel outside diameter before threading
- Caliber, ie. the diameter of the hole
You want to ensure there is sufficient thickness of material left on the barrel after threading. For example, cutting a thin barrel with a large caliber to a small major diameter is not the best option.
However you also want to make sure the thread grooves are sufficiently deep to achieve a strong connection with the suppressor. Theoretically, the deeper the thread grooves, the less chance of the suppressor "slipping" off. With a heavy barrel and a small caliber, you can afford to cut deeper threads while maintaining sufficient residual barrel thickness.

So it's all about finding the best balance point, and is probably best left to the suppressor fitter or gunsmith to decide.

With my rifles 22cal gets 1/2x20 thread everything above that bar a facory threaded rifle gets a 14x1

Have you looked at Greystone suppressor?

Greetings Delphus,
Both my .308 rifles have 5/8"x 24 UNEF. One came threaded and I had the second one threaded the same although each has its own suppressor. If I get round to suppressing my 6.5 x 55mm rifles theirs will be 14 x1mm. Ditto the .223 will be 1/2"x 24 UNEF. This stops me getting the suppressors mixed up, a small thing perhaps but fail safe is always best. Your rifles your choice however.
Regards Grandpamac.

I use a 30 cal suppressor and dont own anything over 30 so dont have to worry about a different suppressor for every different rifle and supression seems to work well

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Originally Posted by northdude

I use a 30 cal suppressor and dont own anything over 30 so dont have to worry about a different suppressor for every different rifle and supression seems to work well

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Greeting Northdude,
My son uses a .30 calibre suppressor on his .284 which seems to work well. One of my suppressors is a muzzle forward model and I had thought of sharing it with some of my old soldiers, 6.5mm, .30 and .303. None of them will be fired all that much so it would probably work well. We will see.
Regards Grandpamac.

Go to DPT with your rifle and get them to do the whole shebang. Job done. No heartache. Taught me a bit on my last visit in November. Walked out with the magnum 243 suppressor. Fantastic balance . Going back for my 223WSSM shortly or in November. The dude has come a long way from Tokoroa. Credit to him.

Delphus being in Timaru is long way from dpt in hamilton.

I do like the DPT suppressors BUT living where I do...its gunworks spartan for me....and with your 223,how much length will you actually save???past the muzzle,maybe inch tops....back behind suppressor yes the dpt is shorter...but the spartan going back further SEEMS to make rifle balance better ,unless you going to make barrel really short and want to butt suppressor up against stock you really wont gain a hell of a lot.

also if Im reading your post correctly...you only want to change suppressor type...not looking to shorten barrel...you COULD just buy DPT with correct thread....but seriously I suggest you borrow one and try it for balance and length before forking out hard earned $$$$ to change from what you have that is working fine.

I was looking to try and save a bit of coin and buy a second hand supressor when it came up, even if it was a different thread than my barrel, and just have the barrel cut and rethreaded to whatever the supressor thread was. I’ll just save up a bit more and buy a new one. Or just buy a new DPT and keep the length the same for now. Take a look at the comparison pic(obviously bottom is hardy not dpt), mine is the top one. Same length barrels in both photos, but mine is significantly longer. It just feels too long in the hand, especially as half of my wallaby shooting is on the back on a canam.

Attachment 165035

Generally you want to make sure that the major diameter of the thread is as close to the original external barrel dimeter as possible - to maintain as much wall thickness in the barrel as possible.
This is why the fatter the barrel, generally the large dia the muzzle thread will be because you want to maintain as much thickness as possible.

Basically muzzle threads are usually chosen because A. popularity of accessories in a given thread. B. remaining meat left on the barrel with chosen thread.

Its debatable what if any effect an undersized thread would have on a large dia barrel - The main effect id be concerned about is the potential for the thin parts of the barrel to heat faster than the thick parts. When steel gets hit it distorts. This could potentially lead to inconsistent distortion caused by heat where the end of the barrel changes (due to heat) at a different rate/degree to the rest of the barrel; potentially causing consistency issues at different barrel temps.

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Originally Posted by Delphus

So I have been wondering this for a while. I understand the difference between threads, the fact that there are a certain amount of turns cut per inch etc. What I don’t know is what the different threads are used for? Can any thread be cut into any barrel? Are some threads used for specific barrels? I’m looking to cut down my .223, but also want to replace the current gunworks suppressor for a dpt. I have passed up on a few second hand supressors in the past because they were the wrong thread for the rifle. Can I buy another threaded suppressor and cut the barrel to suit?

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The short answer is there are thread sizes suitable for different calibers . If the two rifles you have in the pic are the same caliber but different threads it is quite likely they are just metric vs american threads , possibly depending on whether they are factory threaded and the manufacturer - ruger or howa for example - or threaded aftermarket . If you can identify the thread on your rifle chances are you can buy a supressor in the required thread , but if dpt will probably need the bush machined to suit the barrel .
For example the common rimfire thread used in nz is 1/2 x 20 but the americans always seem to like 1/2 x 28 ....

Most of mine are metric threaded.
The old JW15 (1980's) is 1/2x28, sons ex Ar was 1/2x20,
Heavy barrel 223 and 243 are 14x1,
Light barreled 358 is 14x1, possibly could have been 16x1 but would not have had much shoulder at the end of the thread to butt the inside of the silencer up against.
Z
That bottom silencer looks like a Hardy, very short front overhang of about 80mm on the compact version.

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Originally Posted by Delphus

I was looking to try and save a bit of coin and buy a second hand supressor when it came up, even if it was a different thread than my barrel, and just have the barrel cut and rethreaded to whatever the supressor thread was. I’ll just save up a bit more and buy a new one. Or just buy a new DPT and keep the length the same for now. Take a look at the comparison pic(obviously bottom is hardy not dpt), mine is the top one. Same length barrels in both photos, but mine is significantly longer. It just feels too long in the hand, especially as half of my wallaby shooting is on the back on a canam.

Attachment 165035

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now RETAKE photo with rifles properly side by side....bottom rifle is 2" further back..look at the trigger guards and ends of forestocks...

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Originally Posted by Micky Duck

now RETAKE photo with rifles properly side by side....bottom rifle is 2" further back..look at the trigger guards and ends of forestocks...

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I was lining up where the barrels meet the receivers:) one is a .270 one a .223 :)

your gunworks suppressor also appears to be one of the early ones....posibly made by Robbie himself....you could go fatter and shorter in same brand.... but I compared a long skinny spartan,SIMILAR to yours,and 5 baffle DPT on same rifle...my old 270...overall length difference was about an inch so I DONT BELIEVE YOU WILL GAIN A HECK OF A LOT,unless you decide to shorten barrel at same time.
DUCKHUNTERS add says 5" forward of muzzle for the 35mm spartan.... check and see what DPT says then weigh it up. I dont have a DPT here to measure. you COULD run dpt with less baffles of course which would decrease length at expense of more noise.....

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Originally Posted by ChrisW

Generally you want to make sure that the major diameter of the thread is as close to the original external barrel dimeter as possible - to maintain as much wall thickness in the barrel as possible.
This is why the fatter the barrel, generally the large dia the muzzle thread will be because you want to maintain as much thickness as possible.

Basically muzzle threads are usually chosen because A. popularity of accessories in a given thread. B. remaining meat left on the barrel with chosen thread.

Its debatable what if any effect an undersized thread would have on a large dia barrel - The main effect id be concerned about is the potential for the thin parts of the barrel to heat faster than the thick parts. When steel gets hit it distorts. This could potentially lead to inconsistent distortion caused by heat where the end of the barrel changes (due to heat) at a different rate/degree to the rest of the barrel; potentially causing consistency issues at different barrel temps.

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Also note that you also want enough taken off the outside for the suppressor to have a shoulder to contact. If there is not enough shoulder then you can run into issues where the harder barrel metal can damage the starting parts of the thread.

Useful summary - thread options for different muzzle diameters.

Attachment 185233