Bill Calfee
Gun Fool
How I would deepen a chamber?
CYA friends:
Even though I doubt I have much influence with the Almighty, I'd start deepening a chamber with a prayer.
Cause it's so difficult to do perfectly.
_____________________________
Chambering using a reamer:
(For folks who bore chambers, one of them will have to describe the process.)
The main problem with trying to deepen a finished chamber, is that, when the chamber is slightly enlarged by the finishing process the reamer flutes lose their support.
Therefore..........................
The reamer has to be totally guided by the pilot, only.
____________________________
Before I proceed, I do not use tight fitting pilots, for a reason.
Taper lapped bores seldom remain truly round land top to land top, at the breech end, even if the "as buttoned" blank was perfect to begin with.
This is just the nature of taper lapping, since most of the lapping strokes are at the breech end of the blank.
And of course a reamer pilot, pilots off of the land tops.
Here's the reason I do not use tight fitting pilots:
The beauty of using a reamer to cut a chamber, is that, the reamer will "center on the distorted mass" at the breech end of the blank, if, you give it its head.
In other words if left alone, the reamer will find the best "compromise of location" to center the chamber on the slightly "out of round" land tops.
And keep something in mind here:
If a bore is properly taper lapped, the lands and grooves, although slightly out of round at the breech end of a blank, will be out of round together.
( This is why I don't believe I could bore a chamber, because how does one indicate an out of round bore/groove situation that exists in most taper lapped barrels?)
So a reamer, if left alone, will do the best job of compromising the proper location for the chamber, in a taper lapped blank.
____________________________
But.......................
Deepening a finished chamber is a different story.
The pilot has to do all the centering, since the flutes have lost their support.
_______________________
If I had to deepen a chamber, here's what I'd do:
I would use a tight fitting pilot......even if I had to make one special.
Keep something in mind here:
There's clearance between the OD of the pilot and the land tops...
Plus, there's clearance between the OD of the pilot shaft of the reamer and the ID of the pilot itself.
Therefore, I'd remove the pilot, clean the the ID of it and the OD of the pilot shaft of the reamer, with mineral spirits, this since I use lard oil to chamber with, and mineral spirits reduces lard oil.
Then thoroughly dry both the pilot and reamer.
Then I'd apply cup grease to the ID of the pilot and OD of the pilot shaft of the reamer.......then put the pilot back on the shaft and rotate it, and slide it on and off the shaft until the cup grease was thoroughly distributed.
Then I'd re-install the pilot retaining clip, or screw, and wipe off the excess cup grease with a clean paper towel.
Then the reamer goes into the refrigerator until the moment I'm ready to deepen the chamber.
(I'm only going to deepen the chamber a few thousandths, so one pass is all that should be necessary.)
What this process with the cup grease getting cold does, is to completely eliminate the clearance between the pilot and reamer.
No, the pilot will no longer rotate when you deepen the chamber, which means nothing as far as scratching the land tops...
Properly used, a solid pilot reamer will not damage the land tops any more than a floating pilot reamer.
____________________________
I'd have the barrel completely set up and everything ready to go, then at that moment I'd get the reamer out of the refrigerator, and do the deed.
Your friend, Bill Calfee
___________________________
PS:
There would be one advantage to deepening a chamber by boring, that is, the existing chamber could be indicated off of.
Exactly how the boring bar would be handled, in such a way, as to keep from ringing the chamber when starting the cut, I don't know.
If someone who bores chambers would care to comment, please feel free to do so....
CYA friends:
Even though I doubt I have much influence with the Almighty, I'd start deepening a chamber with a prayer.
Cause it's so difficult to do perfectly.
_____________________________
Chambering using a reamer:
(For folks who bore chambers, one of them will have to describe the process.)
The main problem with trying to deepen a finished chamber, is that, when the chamber is slightly enlarged by the finishing process the reamer flutes lose their support.
Therefore..........................
The reamer has to be totally guided by the pilot, only.
____________________________
Before I proceed, I do not use tight fitting pilots, for a reason.
Taper lapped bores seldom remain truly round land top to land top, at the breech end, even if the "as buttoned" blank was perfect to begin with.
This is just the nature of taper lapping, since most of the lapping strokes are at the breech end of the blank.
And of course a reamer pilot, pilots off of the land tops.
Here's the reason I do not use tight fitting pilots:
The beauty of using a reamer to cut a chamber, is that, the reamer will "center on the distorted mass" at the breech end of the blank, if, you give it its head.
In other words if left alone, the reamer will find the best "compromise of location" to center the chamber on the slightly "out of round" land tops.
And keep something in mind here:
If a bore is properly taper lapped, the lands and grooves, although slightly out of round at the breech end of a blank, will be out of round together.
( This is why I don't believe I could bore a chamber, because how does one indicate an out of round bore/groove situation that exists in most taper lapped barrels?)
So a reamer, if left alone, will do the best job of compromising the proper location for the chamber, in a taper lapped blank.
____________________________
But.......................
Deepening a finished chamber is a different story.
The pilot has to do all the centering, since the flutes have lost their support.
_______________________
If I had to deepen a chamber, here's what I'd do:
I would use a tight fitting pilot......even if I had to make one special.
Keep something in mind here:
There's clearance between the OD of the pilot and the land tops...
Plus, there's clearance between the OD of the pilot shaft of the reamer and the ID of the pilot itself.
Therefore, I'd remove the pilot, clean the the ID of it and the OD of the pilot shaft of the reamer, with mineral spirits, this since I use lard oil to chamber with, and mineral spirits reduces lard oil.
Then thoroughly dry both the pilot and reamer.
Then I'd apply cup grease to the ID of the pilot and OD of the pilot shaft of the reamer.......then put the pilot back on the shaft and rotate it, and slide it on and off the shaft until the cup grease was thoroughly distributed.
Then I'd re-install the pilot retaining clip, or screw, and wipe off the excess cup grease with a clean paper towel.
Then the reamer goes into the refrigerator until the moment I'm ready to deepen the chamber.
(I'm only going to deepen the chamber a few thousandths, so one pass is all that should be necessary.)
What this process with the cup grease getting cold does, is to completely eliminate the clearance between the pilot and reamer.
No, the pilot will no longer rotate when you deepen the chamber, which means nothing as far as scratching the land tops...
Properly used, a solid pilot reamer will not damage the land tops any more than a floating pilot reamer.
____________________________
I'd have the barrel completely set up and everything ready to go, then at that moment I'd get the reamer out of the refrigerator, and do the deed.
Your friend, Bill Calfee
___________________________
PS:
There would be one advantage to deepening a chamber by boring, that is, the existing chamber could be indicated off of.
Exactly how the boring bar would be handled, in such a way, as to keep from ringing the chamber when starting the cut, I don't know.
If someone who bores chambers would care to comment, please feel free to do so....
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