I just started reloading and I've encountered a problem already. I am reloading 7mm Rem. Mag with Nickle plated cases. After seating bullets i noticed some of the cases were crushed and otherwise deformed. Also, some copper from the jacket of the bullet was scraped up and built up along the neck of the round. Any comments on why this could be happening would be appreciated.

What equipment are you using? Specifically dies?
Perhaps an incorrectly sized neck bushing (if applicable)?
Chamfer and debur the necks?
Wrong bullet?

ETA Try running an empty case into your seater die. Possibly hitting the crimp ring way too soon.

1. Back your seating die off of the shellholder by about .05". Most seating dies have a crimper built in, and that crimp rim can crush the case if there isn't a cannelure present on the bullet for the case mouth to be crimped into (you never need a crimp with most cartridges for modern bolt action rifles).

2. Chamfer the insides of your case mouths. The sharp edge of the case can shave the bullets severely.

3. Start over and read everything in the Lyman Handloading manual before actually attempting to load any shells.

Have fun and good luck!

I'm using RCBS dies(3-die) and press. Nosler .284 140gr BT I did kinda half-assed chamfer and debur(I'm sure i could have done a more thourough job). I was thinking that the sizer die could have been too close. I'll try to do a better job prepping the cases and back off the seater die a bit and tell you guys what happens.
Thanks

I`m betting Stonecreeks idea that the crimper is too low is causeing your problem. Back the seating die out and with a EMPTY case in the shellholder raise the ram and screw the die down until you feel contact with the case. Back the die off a quarter turn and lock the ring, use the seating stem to adjust the bullet depth. As for crimping I wouldn`t worry about it, most cartridges will work just fine without one.

That is very good advice. It sounds like the crimper is hitting too hard to me also.

Thanks a lot for the advice fellas. I won't be able to give it a shot until this weekend but i'll be sure to let you all know how I fared!