Does a leade errode at initial angle?

[Shawnba67]

I looked a bit, couldnt find an answer to suit me.
So you have a chamber cut with a 1.5 degree leade. Lets say 500rds later you've erroded away .030. Is your leade still 1.5 degres and just .030 deeper?

 

[msinc]

I looked a bit, couldnt find an answer to suit me.
So you have a chamber cut with a 1.5 degree leade. Lets say 500rds later you've erroded away .030. Is your leade still 1.5 degres and just .030 deeper?

Erosion does not follow or happen on a straight or flat plane. It happens the most closest to the case mouth, which is where the most heat is. So, if you have a 1.5 degree throat angle and you increase the diameter closest to the case mouth then it makes sense that the angle increases, but only in that area the burn happens. The area forward of the burn maintains it's angle because there is nothing happening there to change it. However, burn it enough and yes, it will change.
All that said, when dealing with angles the depth is relative. When you say "depth" I am thinking you mean length the bullet can be seated out further to "touch" the lands??? Because the throat or lead is an angle a few thousandths burned away can allow the bullet room to seat out in length more. I am probably doing a bad job of explaining this and I know it is confusing, for example...if the lead were a "step" then yeah, .030" burned away would allow the bullet to move out .030". But, because it is an angle a few thou off the sides will allow the bullet to move out more. This is apples and oranges though, because again, the lead doesn't burn out like it is being honed or reamed at the same angle it was originally cut. Bottom line, you may only burn out .006" or .007" and the bullet might have to move .025" or .030" to get back out to touch the lands.

 

[Alex Wheeler]

No.

 

[mikecr]

I don't see why it would still be the same angle.
The heat & flow of it would likely be higher where there is less resistance to it, which would be nearer to bore than groove. So where there is material removed, that should begin at the bore-land junction, eroding deeper and deeper over time -toward groove. This, changing overall angle from groove to bore.
Just my perspective, which is not supported with measure.

 

[geo.ulrich]

No.

As Alex said no, but to expand the post it does not erode evenly either.

 

[alinwa]

I don't see why it would still be the same angle.
The heat & flow of it would likely be higher where there is less resistance to it, which would be nearer to bore than groove. So where there is material removed, that should begin at the bore-land junction, eroding deeper and deeper over time -toward groove. This, changing overall angle from groove to bore.
Just my perspective, which is not supported with measure.
View attachment 1064902

OHHhhhh NOOooooo!!! You made PICTURES!!!

10 yrs from now this diagram will be shown on forums as "how lands erode" and your illustrations will enter into Thee Lore Of Thee Campfire Ballistical Expertes acros't the world.......

 

[Shawnba67]

PARTIAL QUOTE

Just my perspective, which is not supported with measure.
View attachment 1064902

This perspective matched my hypothisis pretty dead on.

 

[gunsandgunsmithing]

PARTIAL QUOTE

This perspective matched my hypothisis pretty dead on.

Mine too! Lol!

I would speculate it to be much like I think barrel break in goes...(I know)

Imagine a piece of metal fresh out of a bandsaw. Now run a torch across it. The sharp edge/burr will glow red and almost instantly burn away but the rest of the part, barely even warm.

I read a few years ago about Smith and Wesson having trouble with flame cutting of the frames on their 500s&W revolvers..maybe from their custom shop. Guess what they did to fix it..polished the area that was being flame cut! I suppose the reasoning is that erosion is easier to prevent than to stop. The theory is that the flame will flow over a smooth surface without transferring much heat, but add a burr...and it will erode rapidly and uncontrollably.

 

[geo.ulrich]

Mike, Yes and no yes it will erode less as you said burrs will burn off or harden then shear off. the heat will still cause heat checking which will constrict the area first then start to pull steel that has checked off. this is the erosion we see where the lands are almost worn off.

 

[alinwa]

Basically...."what George said"

But


I just chambered a 6mm barrel last weekend. The barrel had been a 6BR for 755 rds

I ordered a barrel from Bruno's....I SCREWED UP THE ORDER..... Bruno's did nothing wrong. Point is, I wanted to fireform a bunch of brass and find some die settings etc. Match next week.....not a load one

No Barrel.

I've got 3 reamers....

So I cannibalized this Shilen barrel off a live varmint setup.

I had to use a 2 tenths undersized bushing to indicate the barrel in, pre-drilled an inch or so, OPENED UP a tenth so now I'm at only one tenth under.... and by the time I got into the leade area I was using the same size bush as the muzzle. I'm figgering just over an inch of the throat was buggered.

RE-indicated, pre-bored, timed and chambered.....

Grabbed up some cases from another rifle entirely and had at it.

Now I have a problem. The gun is competitive......

My barrel came in today but time is short........

So I'ma' shoot the match with it....

Prolly will give up the ghost halfway thru LOL

Or not.

 

[Link]

Mine too! Lol!



I read a few years ago about Smith and Wesson having trouble with flame cutting of the frames on their 500s&W revolvers..maybe from their custom shop. Guess what they did to fix it..polished the area that was being flame cut! I suppose the reasoning is that erosion is easier to prevent than to stop. The theory is that the flame will flow over a smooth surface without transferring much heat, but add a burr...and it will erode rapidly and uncontrollably.

Do smiths polish leads to prevent erosion ?

TY Don

 

[Dusty Stevens]

Do smiths polish leads to prevent erosion ?

TY Don

Yes but not to prevent erosion. You cant stop that. And to even muddy it up more not only does it not erode at the same angle it erodes each land different