I recently took possesion of a friend's 7-30 Waters to make ammo for him to hunt ...I'd never fired a Contender a lot before.
I used some .375 Winchester brass I acquired from Mr. Reed sized for 7-30 Waters. I annealed them and then turned down the necks to a nominal .0085 thickness in order to allow about .004 for bullet release in the .305-.306 chamber neck. After full length sizing w/o an expander, I used a mandrel to size the necks.
I used Fed GM210M primers , Sierra #7250s (OAL 2.815), and Varget powder ranging 33 to 34.8 grains.
A 2x Leupold was mounted after lapping the rings and shimming the rear with a .020 shim. I also added a couple of 6mm washers to float the forend; I set the screws with blue Loctite.
All I can say is WOW. I was setting off my car alarm about 30' behind me. Warm but safe pressures..no egregious head expansion...and no primer cratering. 10 shot groups at 50 yards were variously sized ragged holes around 34 grains or so.There is some real whitetail fetcher loads coming up..A lot of folks were asking "What is that?"....
Impressed with the 7-30 and the Contender...