Do I need to trim unfired 7mmRemMag brass

[CRNA]

I am going to reload some unfired Winchester brass (7mmRemMag). My Sierra manual calls for a trim length of 2.490". My new brass measures 2.495" and this is before being sized. Is it standard for unfired brass to be a little long?

 

[johnnyk]

It's not important if they're a little longer than the trim to length. That length is a guide to keep you safe from pressure which is caused by excessive case length. If the case gets too long it will extend past the cut chamber and into the rifling and "pinch" the bullet.
That being said, every cartridge has a OAL. Truth is most rifle chambers are longer that this number. Sinclair makes a tool for finding your chambers true OAL.
While it is important to not let you cases get too long, I think it's more important to have them all the same length. Consistency (in every aspect) is the key to accurate reloads. JohnnyK.

 

[sp6x6]

If mine where long I would trim, chamfer,neck size to get the odd dent out,maybe uniform primer pocket. Then probably good for a few shoots

 

[CRNA]

That was exactly what I planned on doing. Thanks for the reply. Saw you are in Montana. Man, I would love to visit there sometime. Would love to hunt there even more. Every picture I have ever seen from there looks like heaven.

 

[boomtube]

"Montana... Every picture I have ever seen from there looks like heaven."

Drive over the southern end of that Blue Ridge Parkway thing, there's a Park down there that IS heaven! (Well, the parts that don't have hoards of tourists crawling over it like ants is.)

 

[CRNA]

Boomtube!!! Howdy howdy. Yeah, the Blue Ridge Pkwy is very pretty. I guess it's just like anything else tho, you take it for granted when it's right in front of you. My parents used to take us up there as kids just to ride and look at the mountains. I guess I just got bored with it after so long. Good to hear from you.