Bill Calfee
Gun Fool
Friend Bill Johnson
Friend Bill Johnson:
I've started a new thread because the other thread about this subject was getting way too long....
I did get a good close-up picture today....showing what one sees when they try to measure leade length using a dial caliper, and, showing the actual beginning of the leade, which one can not visually measure....cause it can't be seen with the naked eye....most generally...
But before you look at the picture, I think I need to post some chamber design information.....
My chamber that I designed years ago is very simple....
It's .2250" diameter, straight sided, no taper, with a 2 degree leade......and it does not cut for the rim so I can vary the depth as I need to for different rifling patterns and various bore and groove sizes...
Here's the part that most folks probably overlook:
When you have a .2250" diameter chamber at the beginning of the leade, then a straight 2 degree angle into the bore of a barrel like yours, with say a .2218" groove diameter....( land top to land top is the bore diameter)
This means there is .0032" of the leade free cut before the leade actually starts cutting the lands proper...
Or, .0016" per side of the chamber.....
So this area is not land cut when a bullet is inserted then removed....
So, if one tried to measure the leade length with a dial caliper, visually, this free cut of the leade in not seen, nor measured....
Now, here's the picture:
Bill, if you look closely you can see the actual start of the leade.....it's a very faint line just ahead of the wax groove that's just in front of the case mouth/crimp....
By the way, this chamber is in a 6 groove Douglas barrel......
Oh, and one other thing....
This barrel has a perfectly center chamber, which you can tell by how even the faint line showing the beginning of the leade stays away from the wax groove just to the rear of it....look closely...
If the chamber were not perfectly centered this faint line would vary in distance from the wax groove that's in front of the case mouth/crimp.
Your pistol fool friend, Bill Calfee
______________________
PS:
Bill, I enlarged the picture so you can better see the faint line where the leade actually starts..
Friend Bill Johnson:
I've started a new thread because the other thread about this subject was getting way too long....
I did get a good close-up picture today....showing what one sees when they try to measure leade length using a dial caliper, and, showing the actual beginning of the leade, which one can not visually measure....cause it can't be seen with the naked eye....most generally...
But before you look at the picture, I think I need to post some chamber design information.....
My chamber that I designed years ago is very simple....
It's .2250" diameter, straight sided, no taper, with a 2 degree leade......and it does not cut for the rim so I can vary the depth as I need to for different rifling patterns and various bore and groove sizes...
Here's the part that most folks probably overlook:
When you have a .2250" diameter chamber at the beginning of the leade, then a straight 2 degree angle into the bore of a barrel like yours, with say a .2218" groove diameter....( land top to land top is the bore diameter)
This means there is .0032" of the leade free cut before the leade actually starts cutting the lands proper...
Or, .0016" per side of the chamber.....
So this area is not land cut when a bullet is inserted then removed....
So, if one tried to measure the leade length with a dial caliper, visually, this free cut of the leade in not seen, nor measured....
Now, here's the picture:
Bill, if you look closely you can see the actual start of the leade.....it's a very faint line just ahead of the wax groove that's just in front of the case mouth/crimp....
By the way, this chamber is in a 6 groove Douglas barrel......
Oh, and one other thing....
This barrel has a perfectly center chamber, which you can tell by how even the faint line showing the beginning of the leade stays away from the wax groove just to the rear of it....look closely...
If the chamber were not perfectly centered this faint line would vary in distance from the wax groove that's in front of the case mouth/crimp.
Your pistol fool friend, Bill Calfee
______________________
PS:
Bill, I enlarged the picture so you can better see the faint line where the leade actually starts..