Hi this is my first post so take it easy on me. I own a remington 300 sa ultra mag with a 22 inch barrel. Im looking for any advice on handloading for this rifle. I am having trouble finding ammo and I also want better performance. the gun is used primarily for alpine mule deer hunting, I feel comfortable shooting out to 400 yards but I want to shoot farther. Right now I'm using factory 180 grain rem corelok bullets and would like to go to a 150 grain. Any help would be great.