Resize and trim new 45-70 Starline brass??

[Shak3s1977]

Well I picked up 100 new 45-70 pieces of brass from Starline. I read online that this brass will actually shrink during the initial firing?? Should I wait to trim till after I use them? Should I go ahead and resize them? Should I resize and trim before using? What's has everyone else had luck doing? Random length checks show they are kind of all over the place. Within spec but not uniform.Thanks again for the help.

I have always used previously fired brass for my pistols, so this is my first time buying brand new brass and new brass for a rifle.

 

[FROGO207]

Personally l always size my new brass before use. If you do not trim the brass first use a set of calipers and sort by size if you are going to roll rimp the necks. Then trim after first firing just to make them all the same for future crimping ease.

 

[troy fairweather]

always size, and trim if there shorter then trim length. just find the shortest and trim them all to that length.

 

[25-20 WCF]

The final case length after firing depends on chamber dimensions. I recommend firing first, then sizing and trimming. Otherwise you may have to trim twice.

.

 

[rdnktrkr]

When I bought some 6.5x50 rifle brass I sized then trimmed then annealed, after the first firing they were not all the same size but closer than when they were new.
Kinda makes me wonder what tolerance ammunition manufacturers have if new brass needs to be trimmed

 

[ArchAngelCD]

Straight walled cases usually don't need sizing when new. If they are all banged up you can size the top half of the brass to enable seating the bullets without trouble. Note having to process the brass is part of the gun of buying new lol.

 

[Blue68f100]

Starline normally puts a note in with there brass telling you to at a min run a mandrel into the necks to even out any damage during shipping and to remove a non-tarnish protective film. This will give you more even neck tension. I never trim new brass, but do size them. Most of the new brass I have measured is all ready at trim to length. So wait at least to the first firing before considering trimming.

 

[Charlie98]

With .45-70 brass, I run the expander into the neck (RCBS Cowboy dies...) If I don't feel any resistance, I FL size them all. I've bought 2 different 100cs lots of Starline .45-70, I've never had a problem with new case length, but I'm only loading cast with a light crimp into a groove... case OAL doesn't make a whole lot of difference there. I would certainly fire them all, then resize before I got all excited about trimming them.

 

[forty_caliber]

Starline brass has been really consistent for me. Typically, I size and load right out of the box. Size and trim on second run.

.40

 

[Shak3s1977]

Thanks everyone. I'm going to load them up and shoot them all first. I'll hold off on the first trim till after the first sizing. Was worried about getting a better uniform crimp and didn't want to end up with some really short and some longer.

 

[Wis-Harpo]

I read that Starline brass is so clean, that when you resize it for the first time, it squeaks. When I got my 100 rounds of 45-70 brass it did squeak. I had trouble with small dents from the Unique sizing lube used to reduce the sound and to resize smoother and easier. Later ( after resizing the brass) I read on this site years ago, to run the new brass in your tumbler to reduce the smoothness of the new brass. The small dents do come out on the first firing.

 

[Ireload2]

Only trim your cases after they have been fire formed and resized.
If you are concerned that a little variation will affect your crimps be sure to use a Lee factory die. It is not sensitive to case length.