Chamber Question

[hoz53]

Hi everybody--For Practice I just tried rechambering a Remington factory barrel. First time I've tried on a factory barrel. The lands where the chamber ends have points on them. They are shaped like an M instead of being perpendicular to the length of the land. I wish I could include a picture but don't have a way to take one. Why are these points on the lands? I used a brand new reamer and it looks okay to me. Mabie those lands are actually dished in the middle and so the reamer didn't cut there. Any info would be appreciated. Thanks

 

[Alex Wheeler]

The shape of the land. You'll see that in a lot of different barrels. The top of the land is dished. See it on button barrels alot.

 

[hoz53]

The shape of the land. You'll see that in a lot of different barrels. The top of the land is dished. See it on button barrels alot.

Thanks for that info.-- This junk barrel just keeps on helping me learn. I dont know but it seems like it cant be good firing the bullet into rifling like that?

 

[shortgrass]

Thanks for that info.-- This junk barrel just keeps on helping me learn. I dont know but it seems like it cant be good firing the bullet into rifling like that?

"I don't know but it seems like it cant be good firing the bullet into rifling like that?" Bullets are fired into canted land rifling (5R) all the time, and its not the same traditional shape as most would imagine. What about polygonal rifling? That 'hole' isn't even round! Uniformity of the rifled barrels' bore/grooves, proper surface finish, proper relationship of chamber to the rifling, proper chamber dimensions. Think it through before forming a conclusion!

 

[Alex Wheeler]

Thanks for that info.-- This junk barrel just keeps on helping me learn. I dont know but it seems like it cant be good firing the bullet into rifling like that?

Shape of the land wont hurt anything. Its just different. What I have seen it with different styles of rifling the pressure curve is different and requires a different tune.

 

[shortgrass]

Shape of the land wont hurt anything. Its just different. What I have seen it with different styles of rifling the pressure curve is different and requires a different tune.

EVERY barrel requires a little different 'tune' for best performance. No two are identical, close,, but not identical.

 

[Alex Wheeler]

EVERY barrel requires a little different 'tune' for best performance. No two are identical, close,, but not identical.

I think you may have missed my point. If you shoot a dasher or ppc, with your barrel of choice and the same reamer, the load with be within an .1 or .2 on powder and a few thousandths of seating depth. If I chamber a dasher in a 4 groove krieger, I can tell you a load that will shoot. If I cut the same chamber in a 6 groove hart or a 5 groove rock creek, the tune will be a lot different.

 

[tclaunch]

You`ll see the same signature engraved on the bullet, when checking the OAL of your ammo. The key is making sure they are all very close to same length. Setup is everything.

 

[shortgrass]

If every barrel was "identical" there'd never be any need to change the rifling cutter or discard a button for a new one. Is not a .1-.2g change in charge weight or a few thousands in bullet seating depth a "tune"?

 

[Alex Wheeler]

You are right. I may not have done a good job of explaining this. What I mean is, when you switch to a totally different style of rifling the "basic tune" will be different, than what your used to with the barrels you normally shoot. Your powder charge and or seating depth may change drastically.

 

[butchlambert]

I thought the top of the land was a radius from the drill and ream before rifling.

 

[Alex Wheeler]

I thought the top of the land was a radius from the drill and ream before rifling.

You know they are Butch.

 

[okie]

You know they are Butch.

since a couple experts are here, I have a question??
Does the button cut metal out, or push it around?? or a little of both??? thanks

 

[butchlambert]

since a couple experts are here, I have a question??
Does the button cut metal out, or push it around?? or a little of both??? thanks

A button doesn't cut. It irons the shape in the bore.

 

[okie]

A button doesn't cut. It irons the shape in the bore.

ok. thanks for the explanation

 

[shortgrass]

I thought the top of the land was a radius from the drill and ream before rifling.

Read the first sentence of the first post, the OP has a Remington factory barrel he's playing with. It's hammer forged, so it'd take the shape of the mandrel that the bore/rifling is 'formed' around. If the mandrel has some weird shape, so will the inside of the barrel. Same might apply to a button rifled barrel, as the lands and grooves would take the 'mirror image' shape of the button. You would expect the lands to have slight concave radius tops in a cut rifled barrel, the shape of the round hole before rifling, as each groove is cut, meaning metal removed not displaced/formed by a button or beat into shape around a mandrel under a drop hammer

 

[hoz53]

"I don't know but it seems like it cant be good firing the bullet into rifling like that?" Bullets are fired into canted land rifling (5R) all the time, and its not the same traditional shape as most would imagine. What about polygonal rifling? That 'hole' isn't even round! Uniformity of the rifled barrels' bore/grooves, proper surface finish, proper relationship of chamber to the rifling, proper chamber dimensions. Think it through before forming a conclusion!

OK. I hadn't formed a conclusion yet and didn't know that's why I asked the question. Thanks for providing this info to help me.

 

[hoz53]

OK. I hadn't formed a conclusion yet and didn't know that's why I asked the question. Thanks for providing this info to help me.

Thanks Guys-- I didn't expect this much info answering my question and I appreciate it. I learned some things.

 

[boltman223]

I think you may have missed my point. If you shoot a dasher or ppc, with your barrel of choice and the same reamer, the load with be within an .1 or .2 on powder and a few thousandths of seating depth. If I chamber a dasher in a 4 groove krieger, I can tell you a load that will shoot. If I cut the same chamber in a 6 groove hart or a 5 groove rock creek, the tune will be a lot different.

What if it was a four groove Bartlein would it be like the krieger? or is it just the maker/brand thats making the difference?

 

[Alex Wheeler]

What if it was a four groove Bartlein would it be like the krieger? or is it just the maker/brand thats making the difference?

Well, I dont use many Bartlien barrels at all. But a 4 groove Brux will tune close to a 4 groove Krieger. My opinion on the matter is, a 5r barrel changes the pressure curve. The bullet requires less force to engrave into the rifling. I believe thats why the tune can end up being quite different.