I've been shooting factory ammo. at targets just for the brass so I have fire formed brass for my rifle to reload. Today I stoped by a gun shop to look at ammo and they had new 7mm rem mag brass $30 a 100, so I bought 100. I've never used new brass befor, I figure I have to full length size and trim them all. (correct?). The first time I fire these rounds be Will they be accurate or will they be like the factory ammo I've fired.
I have never found a factory cartridge that would shoot very well in this rifle.
Thanks Jamie

i prefer to chamfer inside and out and then run the neck over a lyman " M " die, load and shoot. but i have taken out the expander/decap pin out of my rifle size dies and use a universal decapping die and the lyman M die to expand the case neck.

If I buy new brass, I just measure them and for the moment the size was always right. I just load them with a minimum load, just as always with new components and 'work up'. Try the first 5 in your rifle to chamber before you load the rest of the bunch, just to make sure they chamber well. Check OAL. Afterwards I only neck-size them with Lee Collet Dies. First should not be as accurate as the one to follow because new brass isn't formed yet to YOUR riflechamber.

I've bought both Remington and Winchester new brass in bulk, and consider this to be a great buy. I neck size new brass -- not full length size -- because the necks are sometimes bent or otherwise not properly sized. I also use a flash hole deburring tool to debur the flash hole inside the case. If I've found a max load that works well in my rifle with a given brand of brass, I have no qualms about using new, unfired, brass of that brand to load that max load.

In my opinion there's no need to trim new brass, as I've never seen it be overlength. I do trim my brass after every firing.

I ALWAYS FULL LENGTH size all NEW brass. The new stuff takes a lil abuse in shipping that needs ironed out. I also had a rifle once that had such a tight chamber that if i didnt full length size the new stuff i had trouble closing the bolt. Full length size the first time and eliminate and possible problems. After the first firing i then neck size......