280 GNR

3 would be better. Normally the 405 case should be stepped down to 375 caliber, then 338 or 30 caliber, then 7mm. Try going to 35 caliber first but lube it good and go slow. Don't worry if you get some lube dents as they will blow out in the fireforming.

The 280 GNR is one of our most accurate calibers. Several of our regulars only use it and nothing else. One of my main guys here in the shop, Nate, used it in Africa last year and took several shots well over 200 yards and his was a handgun.

Typically I try to make a long neck below the shoulder line, then neck it to 7mm and seat a bullet. It can look a little odd with a 2-3 stepped shoulder but it will blow out. Fresh brass is the most elastic, old brass can have some splits on firing. Does not hurt anything other than the brass. I actually loaded and shot .280 GNR before I actually had any .280 dies. I used a combination of various dies, including 7mm Mag. lol I'd NEVER tell you exactly how I did it, you have to use what you have and figure it out. It's more fun that way. I liked IMR4895 for a very predictable powder. I was running a 160 gr. at a sedate 2400 fps in a 13+2" braked pistol. I had trouble getting more from the short .280, compared to my smaller 7mm GNR from a 10", what a fireball! It needs a little more barrel to step out.