Yes metric, been a long day making parts in the work shop
5/8x24 confusion
- Thread starter HDShark
- Start date
Rob-E
Well-Known Member
To resect an old thread, I assume this is the same for all the new tikka barrels that are “5/8″-24 muzzle thread”
If you are quoting in fractions then "5/8" is a fraction so imperial or .625" or 10/16ths
Yes, a lot of the European manufacturers now use 5/8”x24 for .30 cal muzzle threads as it’s common in the US.
1/2”x28 tends to appear on the .22 calibres.
It is made confusing by Gun Dealers on their websites stating that sound moderator threads are 5/8x24UNEF.
Today I saw on a website a 5/8x24 Evo bridge advertised, but the Evo mods on the same page were shown as 5/8x24UNEF . I phoned them up and after a chat I got the chap to screw the bridge onto a tikka Roughtec that was on the rack, it fit. So I asked if the Evo mod would fit? He wasn't sure but got it out of the box and screwed it onto the tikka. It fit.
He sounded a bit surprised. I was surprised too as I thought that an extra fine thread was different from a standard thread. So basically I'd spent the last hour Googling and phoning gun dealers for a 5/8x24 and several said that their advertised 5/8x24UNEF's wouldn't fit a Tikka 5/8x24. So I passed up all the 5/8x24UNEF mod's.
What was that old american TV series where the guy said"Confused? You will be" ?
kenbro
Well-Known Member
Just because both screwed on didn’t mean the are both the corrrect thread.It is made confusing by Gun Dealers on their websites stating that sound moderator threads are 5/8x24UNEF.
Today I saw on a website a 5/8x24 Evo bridge advertised, but the Evo mods on the same page were shown as 5/8x24UNEF . I phoned them up and after a chat I got the chap to screw the bridge onto a tikka Roughtec that was on the rack, it fit. So I asked if the Evo mod would fit? He wasn't sure but got it out of the box and screwed it onto the tikka. It fit.
He sounded a bit surprised. I was surprised too as I thought that an extra fine thread was different from a standard thread. So basically I'd spent the last hour Googling and phoning gun dealers for a 5/8x24 and several said that their advertised 5/8x24UNEF's wouldn't fit a Tikka 5/8x24. So I passed up all the 5/8x24UNEF mod's.
What was that old american TV series where the guy said"Confused? You will be" ?
I remember reading about some Americans with their inch lathes being able to make a thread that allowed a barrel to be screwed into a metric threaded action.
KB.
Just when I thought the fog was clearing....... I've lost the thread
AccuracyNut
Member
A 5/8x24 UNEF is indeed the same as a 5/8x24. It's just a lazier way of saying (or typing) it. 5/8 UNEF is the only standard thread form that has 24 TPI (threads per inch).It is made confusing by Gun Dealers on their websites stating that sound moderator threads are 5/8x24UNEF.
Today I saw on a website a 5/8x24 Evo bridge advertised, but the Evo mods on the same page were shown as 5/8x24UNEF . I phoned them up and after a chat I got the chap to screw the bridge onto a tikka Roughtec that was on the rack, it fit. So I asked if the Evo mod would fit? He wasn't sure but got it out of the box and screwed it onto the tikka. It fit.
He sounded a bit surprised. I was surprised too as I thought that an extra fine thread was different from a standard thread. So basically I'd spent the last hour Googling and phoning gun dealers for a 5/8x24 and several said that their advertised 5/8x24UNEF's wouldn't fit a Tikka 5/8x24. So I passed up all the 5/8x24UNEF mod's.
What was that old american TV series where the guy said"Confused? You will be" ?
To give a short explanation of what the terminology means, the 5/8 refers to five eighths of an inch - the outer diameter of the threads - and the 24 refers to the number of threads per inch. The easiest way to explain TPI is if you were to take a set of vernier calipers and set them to a one inch gap, then set the calipers along your threads and count how many peaks are between the two jaws of the verniers, this would be your threads per inch or TPI.
A 5/8x18 UNF thread has a coarser pitch, being 18 TPI.
UN threads - be they UNF or UNEF are both of the Unified thread form, which was originally an attempt to standardise thread forms between America, North America and GB. Of course, this didn't happen, and there are still many different thread forms, including BSF, Metric, BA, BSP, BSP, NPT etc etc.
Another poster in this thread stated that 5/8x24 UNEF is the same as M16x1. THIS IS ABSOLUTELY NOT THE CASE. While the outside diameter is very close (16mm versus 15.875mm - which is 5/8" converted to metric measurement) the pitch of the thread is different, with the 5/8x24 UNEF obviously being 24 TPI and the M16x1 being equivalent to 25.4 TPI.
If one were to put a 5/8x24 UNEF moderator onto a M16x1 muzzle, the threads would bind and, if forced, would certainly destroy the threads on both the rifle and the moderator. The 1mm when quoted in relation to a metric thread refers to the pitch, which is the distance between the peaks of two adjacent threads.
I hope this helps and doesn't add further to the confusion!
AN
Thank you very much. Nice and simple explanation. I only wish I - and several dealers - had read that this morning
Thread info here, note the incorrect use of the word “equivalent”, it would be better to have used “closest”
www.machiningdoctor.com
5/8 - 24 UNEF : Thread Dimensions (Machining Doctor)
5/8 - 24 UNEF : Basic Thread Dimensions (Pitch, minor & major diameters, depth, lead), Tolerance range for all applicable classes and much more
www.machiningdoctor.com
The Roughtec, Ace and Super Varmint are 5/8x24 and have heavier barrels. The Lite has a 15/1. The link below shows them all:
Tikka T3x - The ultimate rifle for accuracy
Tikka T3x rifles combine proven gunsmithing with modern innovation, offering model options for any hunt or training need.
www.sako.global
The UN or M in the terminology will refer to the thread form, or shape of the little ins and outs.
In the unified system if the letters are used (unc, unf, unef) then the thread count isn't needed, it is implied, like 1/2unf will be 20tpi and 1/2unef will be 28tpi, 1/2unc is 13tpi - the tpi count is not needed. UNS should include the count though.
Same with metric threads. The M** should have course, fine, etc after to denote the pitch or state the pitch number itself. Not all M10 threads are the same, there's M10x1, M10x1.25, M10x0.75, etc.
BA threads are worse, I came across these when fixing old aircraft, and some gun makers (PH?) often made their own threads to suit the situation that followed no standards but their own.
The unified national system came about as Britain/Commonwealth and the US tried to get one standard across the board
In the end we were too close to Europe and modern schooling meant we forgot how to count in fractions so the metric system prevailed here. Americans are just scared of change.
In the unified system if the letters are used (unc, unf, unef) then the thread count isn't needed, it is implied, like 1/2unf will be 20tpi and 1/2unef will be 28tpi, 1/2unc is 13tpi - the tpi count is not needed. UNS should include the count though.
Same with metric threads. The M** should have course, fine, etc after to denote the pitch or state the pitch number itself. Not all M10 threads are the same, there's M10x1, M10x1.25, M10x0.75, etc.
BA threads are worse, I came across these when fixing old aircraft, and some gun makers (PH?) often made their own threads to suit the situation that followed no standards but their own.
The unified national system came about as Britain/Commonwealth and the US tried to get one standard across the board
In the end we were too close to Europe and modern schooling meant we forgot how to count in fractions so the metric system prevailed here. Americans are just scared of change.
AccuracyNut
Member
In the case of metric threads used on muzzles, stating the pitch is crucial, as M16x1, as an example, is neither metric course (M16x2) nor metric fine (M16x1.5).
AN.
An extra fine form, I guess.
But you're right, the pitch needs to be mentioned to be sure.
Even the metric is full of problems if not described properly. I hate it when a leaflet states just M16 thread and no pitch info, it can just slow a job down.
Mike, forget all these numbers, think of it in terms of Tits as they all come in various sizes shapes and distances apart.The Roughtec, Ace and Super Varmint are 5/8x24 and have heavier barrels. The Lite has a 15/1. The link below shows them all:
Tikka T3x - The ultimate rifle for accuracy
Tikka T3x rifles combine proven gunsmithing with modern innovation, offering model options for any hunt or training need.
a couple of examples would be a ACME thread (flat top with a wide pitch) or the more
Hope this clears it up.....
Having just bought a 5/8x24 Tikka and a 5/8x24UNeF moderator I can 100% confirm that they are one and the same thread.Thank you very much. Nice and simple explanation. I only wish I - and several dealers - had read that this morning
Rafter
Well-Known Member
The first number is outside diameter, the second is the pitch. In metric it is how many mm per thread - e.g. M14x1 is 14mm od, 1mm pitch. In Imperial the second number is how many threads per inch. Nobody uses BS 55° thread forms anymore, so if the numbers are the same they'll work. 9/16x24 is the same as 9/16x24 UNEF, which are both 9/16" od, 24 threads per inch.
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