Is there a benefit to a larger muzzle thread diameter?

P

pauls

CGN frequent flyer
Rating - 100%
35   0   0
I'll be having a couple barrel blanks threaded soon and will have the muzzles threaded for brakes.

The brake I'm considering has options for 5/8-24 and 3/4-24.
The barrel profile will be .900 at the muzzle.

The question is, having the choice, are there pros/cons to threading it at .750 vs .625?

I have my opinions but would like to hear yours.

Thanks in advance.
 
Commercial availability of muzzle devices of an adequate calibre would be my only deciding factor.

Like you, I'd also choose the muzzle device I want and get the threading to match.

That said, most short action .30 cal or less use 5/8x24 - that's probably what I'd do.

3/4x24 typically is for .22 cal. Though some 9mm brakes also use that threading.

(Edit: I stand corrected, was thinking 1/2-28 for .22 and 9mm)


An uncommon thread for your chosen calibre could also negatively impact resale value, if you care about that.
 
Last edited:
The brake I want is available in both thread diameters, and will be the only brake that the barrel sees.
The rifle is for competition and will last maybe a couple seasons before being shot out and then replaced.

My only consideration at this point is pros/cons of turning a barrel down to one diameter vs the other and any potential influence on accuracy, influence or change to bore diameter etc etc.

I like to overthink things...
 
I did the exact opposite with my T3x since no 308 brakes would fit. Got ATRS to fit a 556 brake and bored it out to 308.

Pretty sure they could set you up with what you need.
 
I don't think there is any advantage to the larger thread in this case... and 5/8x24 is very common.
 
Astute Observer said:
Commercial availability of muzzle devices of an adequate calibre would be my only deciding factor.

Like you, I'd also choose the muzzle device I want and get the threading to match.

That said, most short action .30 cal or less use 5/8x24 - that's probably what I'd do.

3/4x24 typically is for .22 cal. Though some 9mm brakes also use that threading.


An uncommon thread for your chosen calibre could also negatively impact resale value, if you care about that.
Click to expand...

3/4-24 is never used for .22. You’ll find it on .338s and such.
 
Yes, there is a benefit of more rigidity. Most companies go with whatever will fit most effectively, but some like Desert-Tech intentionally go larger.

All DT Srs barrely use 3/4x24
 
guntech said:
I don't think there is any advantage to the larger thread in this case... and 5/8x24 is very common.
Click to expand...


I've read discussions where some say the more you do to the barrel, the greater chance you have of disturbing the bore diameter and potentially imparting a negative or uneven force on the bullet as it leaves the barrel.
I'm guessing that may come down to skill of the machinist more than anything else...

The reason I started the thread was mainly to see if anyone had any thoughts on this, or if the question sparked any new ideas that I hadn't come across elsewhere.

I'm looking this solely from a performance potential of the rifle point of view.
Threading to one size vs the other is the same amount of work and my brake is available in any size so that's not an issue.

Just thought it might be an interesting discussion.
 
Rigidity difference between 5/8x24 and 3/4x24 would be difficult to measure... it's more theory.

The thread diameter of the 5/8 is smaller but the shoulder area is larger... would that lead to better rigidity? All the thread does is hold the brake against the shoulder.

As I said earlier I don't think it makes any difference in your case... but you have not mentioned the bore size...attaching brakes to a 30 caliber bore have been done with 1/2x28 threads with no ill effects.
 
It's a .260
Barrel at muzzle is .900

Again, this is more a theoretical discussion as I doubt either thread diameter will make a measurable difference in my scores, but if there is a "better" way to do it may as well do it now that I have a blank canvas to work with.
 
I believe Knights armament was a big 3/4-24 thread user and indexed on the muzzle as opposed to the shoulder. Something about not putting any stretch on the barrel and the larger thread also leaves more room for shims at the front? I’d prefer 5/8-24 though as the options for 3/4-24 are slim and somewhat expensive. Flash hiders for example are tricky to find in this thread, I found that out after removing the factory device on my Troy PAR.
 
2drx4 said:
3/4-24 seems like a weird thread size for the brake/suppressor market to have landed on, since it isn't UNEF.
Click to expand...

24 tpi was most likely chosen for ease and speed of threading on non metric lathes... the feed can be engaged anywhere as opposed to an index mark.
 
The biggest factor here is how much material will be left after threading. Going to 1/2” thread on a 30 cal rifle you risk of getting bell mouthing at the muzzle that will sometimes affect accuracy.

5/8-24 is common up to 338 caliber.

GST
 
As a side note, if you were to have a .338 suppressor you could use it on e 2/4x24 .308 negating the need for a second suppressor.

If only...
 
gstprecision said:
The biggest factor here is how much material will be left after threading. Going to 1/2” thread on a 30 cal rifle you risk of getting bell mouthing at the muzzle that will sometimes affect accuracy.
GST
Click to expand...

Well it is a risk when you turn a barrel light at the muzzle and if there is any distortion it will definitely harm accuracy...

But of all the 1/2 inch muzzle threads I have done on 30 caliber rifles, I have never observed any 'bell mouthing' or accuracy loss.
 
You must log in or register to reply here.
Back
Top Bottom