300 win mag reload info?

Just bought a remington 700 sps 300 win mag with 26" barrel,loaded up a couple of 150gr nosler ballistic tips with 73.0gr of IMR 4350 and got 3200fps on the first shot and 3300 on the second,did not have time to shoot anymore.
My ? is spacing off the lands, I put a bullet in a empty case backwards and ran it in the rifle,so I have that max length to the lands 2.825,the worked up loads had a oal of 3.375.I have plenty of room to go longer in the mag well.Where is a good starting point to space off the lands?.010, and also moving the bullet out farther do you get more or less velocity.

Thanks for any comments

I plugged what you said into Quickload and it thinks you should be getting 3319 fps 60 kpsi.

How does loading a bullet backwards tell you your seating depth to the lands?

You might check these out –

http://www.benchrest.com/forums/showthread.php?t=34425&page=2

http://www.benchrest.com/forums/showthread.php?t=27109&pp=15&highlight=seating+depth

Not knowing what the base of you bullet was, you may or may not have measured to the starting of the lands. The distance off the lands is measured from the ojive of the bullet, not the base. The ojive of different caliber/brand /weight/design bullets may vary widely.

You need a comparator. 15thousanths off is a good starting point.