Partly it's cost, and you can check that on Midway. Starline 7-08 brass. Starline 260 brass. Technically, they are the same case.
But another, more important (to me) reason is that I do partial length neck resizing. I set up the F/L die a bit higher so the rear/lower portion of the neck remains unsized. The 7mm diameter section will still chamber, but it's nice and snug and tends to center the case better in the chamber, offsetting any potential concentricity issues. Because I use SAAMI chambers, concentricity gets tricky, and this helps (I think) maintain it without steps like narrow necks and neck turning.
Also, the wider neck portion where the shoulder joins can tend to acquire a donut, but by leaving the neck expanded there, any donuts would need to grow considerably to actually become a problem. In fact, they could help with aligning the bullet's axis concentric with the bore axis.
This practice goes back to early BR technique when concentricity was first becoming recognized, butt the standard F/L die was the only resizer die style available. It was taught to me by my Elder Brothers Bill and Bob decades ago. They were shooting BR in the 50's.
This technique allows the resized portion of the neck length to be adjusted, and serves as an alternative to neck turning for managing neck tension. Less resizing length = less tension, and vice-versa. This was how neck tension was maintained in those days, before we got into the more modern methods. Bu it still works, and may be simpler.
Obviously, this is akin to neck-only resizing in that it fails to bump shoulders.
But I find that I can use a basic, standard .308 F/L die as a bump die. I just set it up so the 308 die has the proper shoulder length, and remove the decapper stem to use it as a bump die. This also works with standard 260 brass if you partial neck length resize it similarly. This technique, leaving the rear portion unresized, seals the chamber better. Any carbon staining stops dead, right at the line where the neck gets wider. I use a brass catcher, and simply wiping the carbon film from the necks with a cloth dampened in rubbing alcohol is the only case cleaning I need to do prior to resizing.
Greg
But another, more important (to me) reason is that I do partial length neck resizing. I set up the F/L die a bit higher so the rear/lower portion of the neck remains unsized. The 7mm diameter section will still chamber, but it's nice and snug and tends to center the case better in the chamber, offsetting any potential concentricity issues. Because I use SAAMI chambers, concentricity gets tricky, and this helps (I think) maintain it without steps like narrow necks and neck turning.
Also, the wider neck portion where the shoulder joins can tend to acquire a donut, but by leaving the neck expanded there, any donuts would need to grow considerably to actually become a problem. In fact, they could help with aligning the bullet's axis concentric with the bore axis.
This practice goes back to early BR technique when concentricity was first becoming recognized, butt the standard F/L die was the only resizer die style available. It was taught to me by my Elder Brothers Bill and Bob decades ago. They were shooting BR in the 50's.
This technique allows the resized portion of the neck length to be adjusted, and serves as an alternative to neck turning for managing neck tension. Less resizing length = less tension, and vice-versa. This was how neck tension was maintained in those days, before we got into the more modern methods. Bu it still works, and may be simpler.
Obviously, this is akin to neck-only resizing in that it fails to bump shoulders.
But I find that I can use a basic, standard .308 F/L die as a bump die. I just set it up so the 308 die has the proper shoulder length, and remove the decapper stem to use it as a bump die. This also works with standard 260 brass if you partial neck length resize it similarly. This technique, leaving the rear portion unresized, seals the chamber better. Any carbon staining stops dead, right at the line where the neck gets wider. I use a brass catcher, and simply wiping the carbon film from the necks with a cloth dampened in rubbing alcohol is the only case cleaning I need to do prior to resizing.
Greg
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