Magnum caliber for 600-1000+

[Mike Casselton]

Frank
Off topic and for my own learning regarding the button rifling, why is that?

I'll give that answer a shot.

The button rifled barrels are drilled and then a carbide button that has the reverse impression of the rifling is pulled through the barrel.
This button causes the material in the barrel to be displaced and it becomes the rifling you see.

Done correctly, a button rifled barrel will shoot with any other type of rifling method.

Where the fun begins is when the button does not continue turning at the same rate as it's designed to do. Usually what happens is it skids a bit, causing the rifling to slow its twist rate.


If you've ever owned a boat, a good example would be moving the boat as you hook it up.
The caster wheel, in theory, should rotate and begin to turn allowing you to move the boat.
What we've all experienced instead is the damn thing skidding and not rotating.
This leaves black plastic skid marks on the floor and makes moving the boat into the proper place more difficult.



Imagine the rifling button skidding inside the bore...

 

[warnera1102]

I'll give that answer a shot.

The button rifled barrels are drilled and then a carbide button that has the reverse impression of the rifling is pulled through the barrel.
This button causes the material in the barrel to be displaced and it becomes the rifling you see.

Done correctly, a button rifled barrel will shoot with any other type of rifling method.

Where the fun begins is when the button does not continue turning at the same rate as it's designed to do. Usually what happens is it skids a bit, causing the rifling to slow its twist rate.


If you've ever owned a boat, a good example would be moving the boat as you hook it up.
The caster wheel, in theory, should rotate and begin to turn allowing you to move the boat.
What we've all experienced instead is the damn thing skidding and not rotating.
This leaves black plastic skid marks on the floor and makes moving the boat into the proper place more difficult.



Imagine the rifling button skidding inside the bore...

Thats probably the best analogy ever made! Thank you. My entire lean-to is covered in plastic skid marks haha

 

[Mike Casselton]

Thats probably the best analogy ever made! Thank you. My entire lean-to is covered in plastic skid marks haha

Buy the Bully dual wheel caster.
Keep the pivot lubed.
You can thank me later.

 

[Frank Green]

Frank
Off topic and for my own learning regarding the button rifling, why is that?

What can happen and is common with button rifling is that for starters it's a cold swaging process. When pushing or pulling the button to form the rifling (it displaces material...it doesn't remove the material like cut rifling does). If during the button rifling process if the button hits a hard spot or soft spot in the material it can slow the button down and in effect slow the twist rate down. The button could speed back up to the twist it was doing but if it does you end up with a non uniform twist and/or the button could keep getting slower. If you have a negative twist in the rifling (slower towards the muzzle) either way it makes the barrel more temperamental as to what it will like for a load and or bullet. You for sure don't want a negative twist.

I've seen button barrels that started out at 8 twist for example and end up at 8.75 at the muzzle.

Some button rifle barrel makers are trying to guide the rotation of the button as well because it is an issue.

Look at some of the gov't test barrel specs and depending on the caliber you they will allow up to a +/- .25 for a 30cal barrel for example.

Uniformity is king! The more uniform the bore and groove size are over the length of the barrel, the more uniform the twist, the more stress free the barrel is and the straighter the barrel blank...the more forgiving the barrel is going to be. No way around it.

Cut rifling doesn't induce any stress into the blank where as button rifling does. So for example if you are making a 30cal barrel with a .308 groove size spec...you might have to use a .3115" diameter button (for a close numbers) because of the spring back you will get. Picture a snake swallowing a mouse. Now you get a different lot of steel....that .3115" button might not work good so you have to go to a different size button etc...might be smaller....might be a little bigger.

Cut rifling also produces the most uniform twist rates as well. When we cut rifle the grooves....we are only taking about a .0001" or so per pass.

Later, Frank

 

[Wannashootit]

Button rifling.
Metal displacement, with no removal?
Drive a punch into a piece of steel, that's displacement. The steel previously from the hole that now exists, is now above the surface.

There isn't a part of the rifling button that "scrapes away", or removes steel (far as I know, anyway) behind the button- so isn't this more compression (like hammer forging), and not displacement? Or is my mind just fucked after a long week?

 

[Frank Green]

Button rifling.
Metal displacement, with no removal?
Drive a punch into a piece of steel, that's displacement. The steel previously from the hole that now exists, is now above the surface.

There isn't a part of the rifling button that "scrapes away", or removes steel (far as I know, anyway) behind the button- so isn't this more compression (like hammer forging), and not displacement? Or is my mind just fucked after a long week?

This is the view from the end on a button rifled barrel. Look at the face after it was rifled.

The bore ream finish isn't the greatest looking either. Some will say you don't need to prelap or finish lap a button barrel either because the button rifling will iron out the bore reamer marks! I don't think so bat man! You can see the roughness of the bore on tops of the lands even after button rifling. Look how the metal got displaced on the grooves from when the button entered the barrel blank. Also I've never seen any chips come out of the blank after the button came out. So no chips....steel is deformed...I say displaced...not removed.

 

[LeftyJason]

Button rifling.
Metal displacement, with no removal?
Drive a punch into a piece of steel, that's displacement. The steel previously from the hole that now exists, is now above the surface.

There isn't a part of the rifling button that "scrapes away", or removes steel (far as I know, anyway) behind the button- so isn't this more compression (like hammer forging), and not displacement? Or is my mind just fucked after a long week?

Have you ever messed with making threads?

There is cut threads and there is form/roll threads.

Cut threads the OD is cut to major diameter and ID threads drilled to minor diameter. The thread is then cut and metal is removed to form the thread.

On roll threads the OD is cut to pitch diameter and on form threads the hole is drilled to pitch diameter. The pitch gets pushed to form the crest and root.

Is the pushed metal displaced?

I'm sure on button rifled barrels the bore is drilled to the rifled equivalent of pitch diameter.

Figured that might clear up differences.

 

[kthomas]

So what magnum did the OP settle on?

 

[Elite_KG]

He said 7 mag or 300 win mag. Likely 300 win mag due to quality brass availability, but then someone posted about ADG brass for 7 mag. Page 1 was his last post.

 

[Tactical_Hunter]

So what magnum did the OP settle on?

I decided to go with a 7 rem mag, I have some retumbo and primers on the way. I also ordered my die set yesterday. I haven’t settled on if I wanna build or just try to hunt down a 700 long range for a gun yet. For now I’m just going to try to piece everything else together.

 

[fdkay]

I decided to go with a 7 rem mag, I have some retumbo and primers on the way. I also ordered my die set yesterday. I haven’t settled on if I wanna build or just try to hunt down a 700 long range for a gun yet. For now I’m just going to try to piece everything else together.

Build.
You'll end up doing it anyway. Might as well do it right the first time.

 

[BigRed308]

Build.
You'll end up doing it anyway. Might as well do it right the first time.

True but it’s kind of nice to have the parts to be able to build a “free” rifle.

 

[warnera1102]

Pick you up a cheap 700 la just for the action and slap a remage barrel on it.

 

[Tactical_Hunter]

Build.
You'll end up doing it anyway. Might as well do it right the first time.

That’s kind of what I’m thinking, I may just put a back order in on a stiller predator and wait it out.

 

[Frank Green]

I'll give that answer a shot.

The button rifled barrels are drilled and then a carbide button that has the reverse impression of the rifling is pulled through the barrel.
This button causes the material in the barrel to be displaced and it becomes the rifling you see.

Done correctly, a button rifled barrel will shoot with any other type of rifling method.

Where the fun begins is when the button does not continue turning at the same rate as it's designed to do. Usually what happens is it skids a bit, causing the rifling to slow its twist rate.


If you've ever owned a boat, a good example would be moving the boat as you hook it up.
The caster wheel, in theory, should rotate and begin to turn allowing you to move the boat.
What we've all experienced instead is the damn thing skidding and not rotating.
This leaves black plastic skid marks on the floor and makes moving the boat into the proper place more difficult.



Imagine the rifling button skidding inside the bore...

Well put.....

Later, Frank

 

[Frank Green]

Here is a picture of a button. This is called a combination button. You can see the grooves in the button that will form the lands of the rifling. it also looks pregnant. It has to expand/displace the material in order to form the rifling etc...

Again for example on a 30cal barrel you might be using a .3115" or a .312" diameter button because of the spring back to get it to come in around .308" diameter.