Barrel slugging

[Dusty Stevens]

Vudoo, live or dead chickens, flying pigs, etc how else are you to determine the place to cut the barrel to finish it? Maybe I am unaware of some new tech that gives the same info as slugging? I know I would sure enjoy barrel fitting more if I did not have to go through the process. I'll admit the better the quality of blank (lapping), the less that needs to be done in terms of slugging for determination of spots to cut but who wants to blindly fit a blank to find out many rounds and time later, if it would have been slugged they would have found a bad spot 1/4" back from where it was originally crowned? Way to many stories like that come about and no telling how many barrels have been give up on because of something like that.

Youre talking rimfire with a dead lead slug. Thats a different story. Thanks for chiming in with your expertise btw. We dont get many rimfire specialists in here so we do appreciate you for sure!

 

[X Count]

CORRECT!!
Might as well wave a live chicken over it while doing the Vudoo dance at midnight on a full moon.
Later, Mark
Bartlein Barrels Inc

How do you guys measure bore diameter? Do you do it to every barrel?
Do you use lapping to get to final diameter and cause any deliberate choke?

 

[Tad_Earhart]

Youre talking rimfire with a dead lead slug. Thats a different story. Thanks for chiming in with your expertise btw. We dont get many rimfire specialists in here so we do appreciate you for sure!

I agree that the dead slug side does make a difference. So does the pressure difference in multiple ways. How much spring back is expected from the typical match jacketed bullet?

 

[DShortt]

I agree that the dead slug side does make a difference. So does the pressure difference in multiple ways. How much spring back is expected from the typical match jacketed bullet?

A very intriguing question. Perhaps this might at least in part explain why it was often said that back when 22lr barrels were rechambered to .22Hornet that the accuracy improved substantially?
Probably had more than just spring back of a jacketed round going on but still interesting to think about ......

 

[Dusty Stevens]

I agree that the dead slug side does make a difference. So does the pressure difference in multiple ways. How much spring back is expected from the typical match jacketed bullet?

Im not sure but i figure the copper has pretty good springback then you add in 50,000psi behind it it should fill in pretty good. No way to really figure it out with the lead core pushing it out too. Way too many variables

 

[DShortt]

Im not sure but i figure the copper has pretty good springback then you add in 50,000psi behind it it should fill in pretty good. No way to really figure it out with the lead core pushing it out too. Way too many variables

So what happens to that lead core when the copper jacket springs back? I don't think springback is a property of lead so .....

Or is the idea that somehow the lead core pushes out the copper jacket? When the core is completely surrounded by copper in most instances?

Help me out here because I don't get how this could work.

 

[STS]

It might help to talk about principles of bullet making, and then apply the same material characteristics to this discussion. The "expand up" method allows cup and core bullets to have adequate adhesion between the core and jacket because of the different characteristics of the two metals involved. The jacket is an elastic metal, meaning that it has some spring back to it. The lead core is a plastic metal, or so called dead metal, that does not spring back to its former shape when deformed. So when core seating in a bullet die, the core and jacket both expand up to size, and the core wants to remain at that size. The jacket is elastic and wants to somewhat return to its former size so it firmly grips the core.
When a bullet obturates to bore size, it will stay at that size unless it encounters a tight spot in the barrel. A tight spot swages the bullet back down in size. That's not a desirable situation for the remainder of the ride down the barrel.

 

[DShortt]

It might help to talk about principles of bullet making, and then apply the same material characteristics to this discussion. The "expand up" method allows cup and core bullets to have adequate adhesion between the core and jacket because of the different characteristics of the two metals involved. The jacket is an elastic metal, meaning that it has some spring back to it. The lead core is a plastic metal, or so called dead metal, that does not spring back to its former shape when deformed. So when core seating in a bullet die, the core and jacket both expand up to size, and the core wants to remain at that size. The jacket is elastic and wants to somewhat return to its former size so it firmly grips the core.
When a bullet obturates to bore size, it will stay at that size unless it encounters a tight spot in the barrel. A tight spot swages the bullet back down in size. That's not a desirable situation for the remainder of the ride down the barrel.

Yes, that's how I have always thought about it myself so I find the idea that a jacketed bullet can spring back somehow confusing and against my current understanding of things. Hopefully someone who has some information on how bullet springback can occur will read this thread and offer some insight because I currently don't understand how that could be possible.