Yes it is a .262 chamber and my brass is at .260....my apologies for not making that clear..
Turn the brass to .085" and that will get you to .260 on the loaded round. Probably use a bushing around .258 on the sizer.
I thought I would use Vihtavuori N133 powder to start. Good place to start, use a 63-68 gr bullet.
If I go the Harrels route and the Wilson seater,how do I procede.
I take my new unfired rifle with new unfired brass.
Should I use an expander mandel on the new Lapua brass,before I load it.
You will need to expand prior neck turning, then it should hold a bullet for fireforming, without having to size it.
How do you fireform your brass? Use a bullet around that 63-68, doesn't really matter much, just don't stick a heavy bullet in there or it will be too high pressure. and as much N133 (assuming new unfired Lapua 220 Russian) as it will hold.
Do I trim before fireform? For length maybe, it should be around 1.500", much longer than that and you should trim it back.
How do I necksize the cases for fireforming if if I have to send the fired cases to Harrells first and wait for the die.
If I have to fire the cases several times before sending them off,don,t I have to size them each time I fire them.
If you go this route you should still have enough grip to just hold the bullet in place for 2-3 firings due to elasticity. Not recommended for matches, but to get a few shots of fireformed brass to send to Harrels it should work. You don't really want to resize it, as this will give a more accurate shape of the chamber for Harrels to measure up
God, loading .223 and 6mmbr was like being on Sesame Street.
Not really! You will be learning about tight necks and brass bumping, but the other principles are the same!
Rick