Should I trim new brass

[jmh240]

I'm new to this so forgive me if this is a stupid question. I just got my first box of Lapua 6mm BR brass. Their lengths vary 1.5540 to 1.5555. My question is if they are all that close should I trim them and if so to what length.

Thanks,

Jim

 

[Forum Boss]

I'll usually trim my Lapua 6BR brass after a couple firings when a bit more of a length disparity shows up. I'll set the trimmer to 1.555 or 1.556, and the trimmer barely touches most of the brass.

 

[JHardy]

Paul:

Some do it different -- do you trim before or after the size die?

Jim Hardy

 

[Forum Boss]

I size then trim as I often shoot different loads during testing and some cases swell more than others. Sizing makes them a little more uniform.

 

[jmh240]

I always size before I trim.

 

[rayjay]

For my first 40 or so loadings I ran the sizer ball down as far as possible and just ran the necks over the sizer ball to uniform them.

Once I had some fireformed brass to use for load development and practice I just use new brass as foulers. Now I don't even uniform the necks of new brass. I just seat some ancient 87gr Hornadys I got back in the 70's. This saves my match bullets for shooting groups.

 

[Forum Boss]

Don't necessarily just "give away" that first firing of the brass figuring you need fire-formed cases for accuracy. I have shot some of my best groups with brand new, unfired brass. I run expander down the neck and chamfer inside and out. I'll use 105gr Scenar bullets seated about .015" into the lands,.015" past the point of "first touch" with a Stoney Pt gauge.)

 

[rayjay]

That's what I was doing with the first 40 or so, playing with seating depths and powder charge. I shot some great groups with the new brass.