when to trim?

[tiny68]

I usually fireform my brass and then trim to a consistent length. I am making up some 30BR brass tonight for a new barrel chambered with a Robinett reamer which if I read the print right has a maximum case length of 1.510". So I have to trim this stuff before fireforming. I usually trim to 1.500". After I fireform do I need to trim after or just run with it?

This is a new lot of Lapua 6BR brass I just got from Bruno's. For some reason I don't remember having to do this on the previous brass I made for the 30BR.

Thanks, tiny

 

[jackie schmidt]

Tiny

If you are using the conventional method of necking up the cases with a mandrel to bring the 6mm up to 30 cal, then you will notice that the cases will shorten up quite a bit from the originol 1.560 of the 6BR case. This is a pretty violent operation, a lot of metal changes shape.

Trim them just after you neck them up. One reason is most neck turners rely on a consistant and specific overall length to insure that the cut hits the neck shoulder junction just right on each case.

Also, sometimes the cases will vary on how short they end up after the initial necking up operation. I have seen them be too long for the Robinette chamber. After you fire them the first time, you might even have to go back and check all of them again. .......jackie

 

[Twud]

Check them after every firing. As you shoot the gun you'll learn how often you need to trim. I have a dedicated trimmer for my 22-250 (the gun I use the most) I dont even measure. Just put one in the trimmer, if the mouth is shiney all the way around then they all get trimmed.