Well the weather just plain sucked here today, misty wet crap. So I did the thing that I usually put off, other than cleaning the garage, and trimmed/prepped 6PPC brass for BR rifles. I know this is usually not in the gunsmithing section, but I am offering it here, as so much of a good BR gun is not just in the chambering, but in brass prep too.
First, some math. I have 3 6PPC's, two with .265 neck chambers, one with .262, and the barrels are marked as such. Each has it's own box of brass that stays with it all season, between 20-50 rounds, depending on the gun. Today was .265 day, looking for about .263 neck diameter on the finished round, working out to a neck thickness of .010. All brass was expanded from .220 Russian to a .243 ID neck before neck turning. Lapua brass usually starts north of .271 diameter, after expanding to .243 ID.
I start by turning a mandrel to hold the necks:
I used a bolt and skinned it down to slightly more than .243, about .245, to give a bit of stretch to the neck, to hold it securely.
The DRO is very handy for this project, but don't trust it completely, I mic each piece before removing it from the mandrel, then spot check neck thickness before setting it in the tray.
Cutting the neck diameter:
When cutting the neck, you have to SLIGHTLY cut into the shoulder, to make a smooth transition to the shoulder, after fireforming. The way 6PPC is made from 220 Russian, you trim the neck diameter, then load fireform loads, and blow the shoulder forward. Part of what is the neck at this stage, will be the shoulder after fire forming.
The finished stuff, prior to fireform.
I think sometime soon, I'll make a form tool for the neck, with a little radius to make the blend to the shoulder sweeter. For now, just using the Mark 1 Mod zero, standard issue eyeball.
Hope this helps some of you who normally don't see this kind of stuff. The BR world is a whole 'nuther place, interesting to see what is important there, is not so much here, and vice versa.
First, some math. I have 3 6PPC's, two with .265 neck chambers, one with .262, and the barrels are marked as such. Each has it's own box of brass that stays with it all season, between 20-50 rounds, depending on the gun. Today was .265 day, looking for about .263 neck diameter on the finished round, working out to a neck thickness of .010. All brass was expanded from .220 Russian to a .243 ID neck before neck turning. Lapua brass usually starts north of .271 diameter, after expanding to .243 ID.
I start by turning a mandrel to hold the necks:
I used a bolt and skinned it down to slightly more than .243, about .245, to give a bit of stretch to the neck, to hold it securely.
The DRO is very handy for this project, but don't trust it completely, I mic each piece before removing it from the mandrel, then spot check neck thickness before setting it in the tray.
Cutting the neck diameter:
When cutting the neck, you have to SLIGHTLY cut into the shoulder, to make a smooth transition to the shoulder, after fireforming. The way 6PPC is made from 220 Russian, you trim the neck diameter, then load fireform loads, and blow the shoulder forward. Part of what is the neck at this stage, will be the shoulder after fire forming.
The finished stuff, prior to fireform.
I think sometime soon, I'll make a form tool for the neck, with a little radius to make the blend to the shoulder sweeter. For now, just using the Mark 1 Mod zero, standard issue eyeball.
Hope this helps some of you who normally don't see this kind of stuff. The BR world is a whole 'nuther place, interesting to see what is important there, is not so much here, and vice versa.
