Threading .284 caliber with 1/2×28???

[Lazy D]

Just about every manufacturer of a .350 Legend barrel thinks it's ok to thread them 1/2-28, so I don't think you'll have any issues.

The 350 Legend is very low pressure. Most aluminum 9mm pistol suppressors are rated for that caliber.

 

[shortgrass]

Just about every manufacturer of a .350 Legend barrel thinks it's ok to thread them 1/2-28, so I don't think you'll have any issues.

I'd bet you are very wrong about that! Thread any .358 barrel for 1/2-28 will leave less than .050 wall thickness of the threaded tenon, which is unacceptable to any competent gunsmith or barrel maker.

 

[Lazy D]

I'd bet you are very wrong about that! Thread any .358 barrel for 1/2-28 will leave less than .050 wall thickness of the threaded tenon, which is unacceptable to any competent gunsmith or barrel maker.

They do, but it's like a pistol barrel. Most 9mm barrels are 1/2-28 also. It's just such low pressure they can do that safely.

 

[tbird86]

I'd bet you are very wrong about that! Thread any .358 barrel for 1/2-28 will leave less than .050 wall thickness of the threaded tenon, which is unacceptable to any competent gunsmith or barrel maker.

What still you be sending me for losing that bet?

Ruger American
Anything CMMG
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I'd have an AR built by now if I could find a .350 Legend threaded 5/8-24

 

[tbird86]

They do, but it's like a pistol barrel. Most 9mm barrels are 1/2-28 also. It's just such low pressure they can do that safely.

55,000 psi is low?

 

[WildRose]

55,000 psi is low?

Compared to most centerfire 30 cal and larger rounds yes, that's pretty low. Even the mild 30-06 runs between about 59-62K,

 

[Highlander44]

I've always heard the typical rule of thumb is that only 22 caliber and below should have the muzzle threaded 1/2×28. I've also recently started seeing that rule of thumb stretched to .264 and below for 1/2×28. Read where 1/2×28 isn't recommended for 30 caliber because the wall becomes too thin. Several smith's I talked to said they prefer at least .010 in the wall. I understand all of that.

My question comes to .284 caliber. Specifically 7mm-08 at the 21" length at the muzzle. It would still give me .012 in the wall. I know Fierce and some other manufacturers sell rifles in 7mm Mag and are threaded 1/2×28 with a muzzle brake, but mine would be for a lower pressure cartridge, with a suppressor.

Any experience with or reasons why it's not safe to do so??

Thanks

Precision Armament and others offer brakes 7/16x24 for hunting contour barrels, in situations where the barrel is too skinny to use 5/8x24-

 

[shortgrass]

I guess that makes me a "monkys' uncle". Can't wait until some dumb a88 sticks a can on it that is for .223/5.56mm only! But, anything for a few more of those good ol' American 'green backs'. Gas cans are red, with warnings all over them and a 'special' spout, but they keep on burning themselves up. No wonder a 5gal can is now $20+ at the farm supply. Last week I dung out a .308 casing that had been fired in a .270. Not long ago I had to straighten out a guy who was insisting .32 Win Special was interchangable with .30/30. No wonder his pre-64 Model 94 was about junk.

 

[Canadian Bushman]

Its worth considering how much metal you are taking off, as well as how much you are leaving on.

If you cut a small thread on a thick barrel the crown will often open up .0001/.0002".

The crown is not a good place to do that.

Also, any machinist worth his salt will tell you minor diameter on an OD thread is relative to the radius on the threading insert.

If its smaller than recommended he is gonna cut under that minor referenced in the thread dimensions. If its larger he will hit the PD before he reaches the minor dia.

Minor dia on the OD, and Major dia on the ID are often expressed as a reference, ie (.473), for this reason.

Use the biggest thread available that gives a good shoulder.

 

[Rocketeer77]

I've always heard the typical rule of thumb is that only 22 caliber and below should have the muzzle threaded 1/2×28. I've also recently started seeing that rule of thumb stretched to .264 and below for 1/2×28. Read where 1/2×28 isn't recommended for 30 caliber because the wall becomes too thin. Several smith's I talked to said they prefer at least .010 in the wall. I understand all of that.

My question comes to .284 caliber. Specifically 7mm-08 at the 21" length at the muzzle. It would still give me .012 in the wall. I know Fierce and some other manufacturers sell rifles in 7mm Mag and are threaded 1/2×28 with a muzzle brake, but mine would be for a lower pressure cartridge, with a suppressor.

Any experience with or reasons why it's not safe to do so??

Thanks

Where do you get your 0.012" wall thickness dimensions from. We have a 7mm bore with an OD of 11.8 mm that's 3.8mm/2 = 1.9mm or 0.076" wall thickness.

 

[CrankyYankee]

These days everyone wants to push the limits, even safety limits.

My suppressor is a TBAC Ultra 5 Gen II (30 cal). I have the CB brake installed to make it a direct thread on a few .224 centerfire rifles that are 1/2x28. I was inquiring to see if it was a good idea or not to put it on a 7-08 where the OD of the barrel is .67" at the muzzle. I haven't done it yet... hence the reason for the thread.

The 7-08 currently has a TBAC BA brake in 7/16x28 (I believe) to attach my TBAC 9" BA suppressor. I was hoping to rethread it to host the Ultra 5 instead of the longer and heavier 9" can. But all of that is irrelevant to my original post.

I've learned alot from the replies so far and am grateful for the knowledge. It is for reasons like this, I believe, that LRH forum exists.

Thanks all.

Cranky Yankee

 

[Okanogan]

I'd suggest contacting TBAC directly and seeking their input. I've talked with them in the past and they seem willing to provide technical support. The can also provide the exacr thread and perhaps shoulder specs, should you choose to proceed.

 

[CrankyYankee]

Where do you get your 0.012" wall thickness dimensions from. We have a 7mm bore with an OD of 11.8 mm that's 3.8mm/2 = 1.9mm or 0.076" wall thickness.

Roughly... 1/2" = 12.7mm. Subtract .284" or 7.2mm, and I get 5.5mm or .216". Divide that by 2 and I get .108" radius wall thickness ( I fat fingered a zero in my original post. Meant .12", but I now know that my numbers are not exact after all of the replies. I am not a machinist and the math gives me a headache.

 

[CrankyYankee]

I'd suggest contacting TBAC directly and seeking their input. I've talked with them in the past and they seem willing to provide technical support. The can also provide the exacr thread and perhaps shoulder specs, should you choose to proceed.

Thanks. Already have. But I wanted more info on why some do and some don't. Knowledge is what I seek.