1/2 - 20 threading

[sroc112]

Looking into putting together another Howa barreled action/Bell & Carlson rifle for a potential Elk hunt next year. This would a 300 WM.

The link below is for the medium contour assembly from Brownells. I notice that the blued version is 1/2 - 28 but the stainless is 1/2 - 20. Why the difference just for barrel finish? Also, how difficult is it to find brake options for 1/1 - 20?

HOWA M1500 Barreled Action 300 Win Mag 24" BBL 1/2"-20 Stainless SKU: 430107688 | Brownells

Check out the HOWA M1500 Barreled Action 300 Win Mag 24" BBL 1/2"-20 Stainless SKU: 430107688 available Online at Brownells Today and many more Rifle Receivers & Parts products are available in our Gun Parts Department.

www.brownells.com

What they are considering to be their "medium" contour, would that fit in a stock for cut for "standard" contour? Below.

Bell and Carlson: Bell and Carlson Howa 1500/Weatherby Vanguard, Standard Contour Barrel

Bell and Carlson is a leader in synthetic stock design, technology and manufacturer of the highest quality fiberglass, aramid and graphite gun stocks available.

www.bellandcarlson.com

 

[Wannashootit]

1/2" is pretty skinny for a .30 cal. I've done them, just not a fan- and that's 1/2"-28.
1/2"-20 is awfully coarse... will remove another .017 or so from the barrel wall thickness, doesn't sound like much but I'd keep all I could.
I've never seen a 1/2"-20t brake...

JMOYMMV

 

[Rubicon Precision]

1/2-20 is prob a typo. They’re both prob 1/2-28.

 

[Darryle]

1/2-20 is prob a typo. They’re both prob 1/2-28.

This

 

[LeftyJason]

Some people do non standard gun threads so there isn't a blow up if someone puts a can on it. Agreed 1/2-20 leaves walls too thin. Might not be too bad just for a muzzle brake.

Read about here.

Silencer Saturday 341: The Case For (Some) Non-standard Thread Pitches

Welcome back to another installment of Silencer Saturday.This time we will look at some standard thread pitches and some less-standard ones.Why would any manufacturer use a non-standard thread pitch?

www.thefirearmblog.com

 

[MarinePMI]

Looking into putting together another Howa barreled action/Bell & Carlson rifle for a potential Elk hunt next year. This would a 300 WM.

The link below is for the medium contour assembly from Brownells. I notice that the blued version is 1/2 - 28 but the stainless is 1/2 - 20. Why the difference just for barrel finish? Also, how difficult is it to find brake options for 1/1 - 20?

HOWA M1500 Barreled Action 300 Win Mag 24" BBL 1/2"-20 Stainless SKU: 430107688 | Brownells

Check out the HOWA M1500 Barreled Action 300 Win Mag 24" BBL 1/2"-20 Stainless SKU: 430107688 available Online at Brownells Today and many more Rifle Receivers & Parts products are available in our Gun Parts Department.

www.brownells.com

What they are considering to be their "medium" contour, would that fit in a stock for cut for "standard" contour? Below.

Bell and Carlson: Bell and Carlson Howa 1500/Weatherby Vanguard, Standard Contour Barrel

Bell and Carlson is a leader in synthetic stock design, technology and manufacturer of the highest quality fiberglass, aramid and graphite gun stocks available.

www.bellandcarlson.com

1/2"-20 is a UK standard. Yeah, I know, weird. But here 1/2-28 is the standard. In the UK 1/2-20 is the standard (if not metric).

 

[redbullitt]

1/2 20 pops up on airguns a lot that I've seen, but haven't seen many mainstream firearms here with that going on.

 

[sroc112]

Some people do non standard gun threads so there isn't a blow up if someone puts a can on it. Agreed 1/2-20 leaves walls too thin. Might not be too bad just for a muzzle brake.

Read about here.

Silencer Saturday 341: The Case For (Some) Non-standard Thread Pitches

Welcome back to another installment of Silencer Saturday.This time we will look at some standard thread pitches and some less-standard ones.Why would any manufacturer use a non-standard thread pitch?

www.thefirearmblog.com

There will not be a can on it, I'm in a can-free state. Only a brake.

 

[45-90]

1/2"X20 thread is standard US UNF thread.
Taps and dies available everywhere...as the standard fine thread for 1/2".
The 1/2" X 28 is not, but used in certain industries like the gun industry for muzzle breaks, where it's common there.
If it's not a typo, as there is no reason to change threads between these two steels...
Then go ahead and use a bushing easily made on a lathe, or buy, 1/2"X 20 to 5/8"X24...then install a standard 30 cal brake 5/8"X24.
Or just machine a muzzle brake to fit... with 1/2"X20 thread.

 

[Gunfighter14e2]

For those who don't know thread depth, or have a machinery hand book.

 

[45-90]

So let's correct the miss information.
1/2" X 20 is a standard USA die for 1/2" fine tread, I have one purchased at the local hardware store.
The 1/2" X 28 is special order, extra fine thread...not common ...only common in firearms muzzle break threads.

Next this is exactly what a 1/2" X 20 looks like on a .308" bore.
Not my choice but enough metal with low muzzle pressure not to be a problem at all.

Next is a factory manufacturered barrel with a 1/2" X 28 thread on a 9mm compared to 1/2" X 20 .308" I just made for comparison. Whoa! Talk about a thin wall!..threads and all!

Next is with the 1/2 X 20 .308" barrel threads turned off ...there is still plenty of metal support, for .308" bore.

 

[Thump_rrr]

1/2-20 is prob a typo. They’re both prob 1/2-28.

1/2-20 is very common in europe.
Both my CZ 457's (Canadian imports) have 1/2-20 threading but those are .22LR.

 

[45-90]

1/2-20 is very common in europe.
Both my CZ 457's (Canadian imports) have 1/2-20 threading but those are .22LR.

Metric is probably common in Europe, for most rifles designated for use in European countries. Imports can change that.
1/2"X 20....IS "the standard" for the USA fine thread by the SAE!.... Period...
1/2" X 28 is the odd ball!...not in common use like the 1/2"X 20 thread, found on most hardware stores in the USA.
You have to special order taps and dies that are extra fine...like the 1/2" X 28... from Brownells, tooling outlets like Graingers, or somewhere that sells gun parts...cause that is one of the few places 1/2"X28 is common...is in muzzle devices for firearms...it's not in common use anywhere compared to the SAE coarse and fine threads in use.
The metric similar would be 14 mm X 1.5 mm for their common fine thread designation.
But they could make a non standard extra fine of 14 X 1 mm if they want, for the commy/ European muzzle breaks...it's up to the manufacturer.

My 8.6 Blackout has 18 mm X1.5 mm "the standard" metric fine. You can find a tap at the local hardware store...bore out the 5/8" X 24 and retap with 18 X1.5 mm to fit any American muzzle brake with that thread, to the metric barrel thread, as long as the .338 bullet has clearence... or bore it out too.
Simple, but many whine about the thread size and being metric.