Using a collet neck sizing die--same caliber?

[beatledog7]

I have a chance to purchase a Lee collet neck sizing die intended for 25-06. I am starting to load .257 Bob.

The only experience I have using such a die is with .223, and I use a die sold as a .223 die. But it seems to me as long as that "25-06" die can be set to the proper length, it should work for any .257 caliber load.

Am I missing something?

 

[Scimmia]

Yep, length matters with the collet NS dies. They work by using the shell holder to push the collet up, so the collet has to be the correct length for the cartridge being sized. I know absolutely nothing about the .257 Bob, but if it's close to the same dimensions, it's possible to either grind off some of the bottom of the collet or to use washers around the base of the case to effectively lengthen it.

 

[beatledog7]

Thanks, that makes sense.

After I posted this I went to the Lee website and noted that the part numbers for the 25-06 and Bob collets and collet sleeves are different, while all the other parts are the same. By the time I bought the 25-06 neck die and then the Bob parts, I could just by the whole Bob set.

 

[Steve C]

I don't belive the collet die for the 25-06 will work with the shorter 257 Roberts case.

The collet of the die closes as the slide is pused up by the shell holder to close the fingers around the case neck. Since the die must be specific to the case length for the longer 25-06 it will not size a .257 properly. The neck of the 25=06 starts at 2.1858" while the .257 neck isfrom 1.9117" to the mouth at 2.2330" so the die would onnly size the top .0472" leaving the remaining bulk of the length .7259" unsized.