Negative effects of threading the muzzle

[mike mccormick]

I have always been told that when you turn down a barrels OD substantially, the ID grows some. How much does this effect accuracy? I always try to keep as much diameter on my muzzle devices as possible. Am I chasing shadows? Will a 3/4-24 threaded muzzle be better than a 1/2 -28? Thoughts?

 

[Sniperhandle]

I have always been told that when you turn down a barrels OD substantially, the ID grows some. How much does this effect accuracy? I always try to keep as much diameter on my muzzle devices as possible. Am I chasing shadows? Will a 3/4-24 threaded muzzle be better than a 1/2 -28? Thoughts?

The thought is that button rifled barrels will expand slightly when turned down for threading and cut rifled barrels do not. Button rifling induces stress. Try to stay with the largest thread pitch you can to reduce the effect if it's a buttoned barrel.

 

[L.Sherm]

While button process does induce stress if after proper heat treat is there stress in the barrel? That is the key.
Theres a belief i think that you want atleast .150 per side min. taking into account for minor dia. of threading so bore dia matters.

 

[LHSmith]

How about the practice of some barrel makers to provide a subtle choke at the muzzle when lapping?

 

[urbanrifleman]

I've never seen any effects whatsoever. The only effect I know of is the ever present "Internet effect", which seems to be present in every aspect of gunsmithing, especially barrel production.

 

[DaveTooley]

Just playing CYA, bigger is better but I've done things that made me cringe with no repercussions.

 

[TimS]

I've never seen any effects whatsoever. The only effect I know of is the ever present "Internet effect", which seems to be present in every aspect of gunsmithing, especially barrel production.

Actually I have seen this. After reading about this issue I went to the basement and checked my threaded barrels with pin gauges. Sure enough a larger pin stops where the thread stop. Can’t say that it really matters.

 

[hogpatrol]

As posted, some will open up a skosh, around .0001. In effect this gives the bullet less resistance and a little extra push at the muzzle. In other words, a threaded barrel will have a higher velocity with the same load than an unthreaded one. I saw this on the internet, so it must be true.

 

[urbanrifleman]

Can’t say that it really matters.

All barrels are made from blanks that are usually 1.25 or even larger. The metal is ripped off the surface to create a contour. Then ripped off again to create a muzzle thread.

People (I have seen on the internet) talk like those barrel blanks came out of the drill already contoured. Or if you touch them after contour they will be somehow ruined.

Most of my barrels these days I contour from unturned blanks myself. Haven't seen one ruined yet.

 

[jelenko]

My understanding is button rifle barrel blanks are stress relieved several times during the process of drilling and rifling.

 

[rijndael]

@urbanrifleman - Are you saying that a gradual taper/contour has the same underlying impact on the bore as a 90 degree shoulder at the end of a barrel?

 

[urbanrifleman]

@urbanrifleman - Are you saying that a gradual taper/contour has the same underlying impact on the bore as a 90 degree shoulder at the end of a barrel?

I'm saying barrels are contoured to much smaller diameters than they come from the mill and then the drill.

Every single barrel.

Why would one cut be better or worse than the other?

 

[L.Sherm]

In button barrels steel matters and Heat treat process matters.

 

[SKWERLZ]

My understanding is button rifle barrel blanks are stress relieved several times during the process of drilling and rifling.

This!
A friend works in a OEM barrel manufacturing outfit and they have a few inert gas heat treatment ovens.

I’ve cut a few cheaper factory barrels that did move after cutting
All the higher end buttoned barrels like Shilen and even Wilson and green mountain blanks had no issues.

 

[Sniperhandle]

I've never seen any effects whatsoever. The only effect I know of is the ever present "Internet effect", which seems to be present in every aspect of gunsmithing, especially barrel production.

The information came from Frank Green at Bartlein Barrels.

 

[urbanrifleman]

My understanding is button rifle barrel blanks are stress relieved several times during the process of drilling and rifling.

All barrels better be stressed relieved several times or you have a banana.

I think it's the "I saw this one time in a million times thing that one time" phenomenon that seems to dominate the internet. A story will hit the web where this guy saw this thing "this one time" and then people start using that as the rule rather than the one in a million exception that it is.

Basically, nearly every barrel on the market in America today is very carefully stress relieved. Multiple times.

 

[urbanrifleman]

The information came from Frank Green at Bartlein Barrels.

What information?

 

[Sniperhandle]

What information?

The information about button barrels opening up.

 

[urbanrifleman]

The information about button barrels opening up.

Of course. Makes total sense to me.

 

[mike mccormick]

This phenomenon is not exclusive to barrels, and can be seen when machining any round , tubular stock.