I am looking at a custom 280 Ackley. builder deceased.
the barrel is stamped 280 Ackley X 311 Neck.

I take this to show that the neck is .311

Can it take factory 280 ammo? or must unfired brass be used and have it all be neck sized before fireforming?

thanks

Factory ammo MAY be a risk you don't need. .311"-.284"=.027" Subtract .002" for release and you wind up with .025" for two neck wall thicknesses(is that a word?). Anyway, that's .0125" per wall, and I've seen a fair amount of brass at .013-.014" thick. Measure your neck walls, turn if needed.

I don't know DD. Thicknesses.. thicknessi..??

Apparently you have a "tight neck" chamber on your 280 Ackley. According to the specs, the neck diameter of the chamber should measure .3176-.3196. Your loaded rounds should not exceed at least .003" under the neck diameter and that may be a little tight for some. I am quoting from memory, so my figures may be off. Someone chime in if they are.

You will be needing to turn the necks,..I am betting a factory case will not even chamber in that gun. Turn the necks down so that there is .0005" - .001" clearance between the neck and the chamber neck,..and you'll be good. Your brass should last longer with this set-up due to not being worked as much. It can only stretch .0005" -.001" upon firing,.instead of the normal .003"-.006".

You will need a finished loaded round to measure .309" to safely fire the rifle, get a quality neck turning tool. I have about 100 Remington cases that are already turned to the proper dimention, flash holes deburred and primer pockets uniformed, that I would sell if interested, but it must not be a giveaway price as this is labor intensive to get all done right. The .311" stamped is the actual neck dia. for that chamber, the loaded round must be less than that. Also I have been able to use standard Redding dies to resize, there is still enough meat in the neck for bullet grip after resize, no need for bushing type die. You will like this round, The bullet I use is a Nosler 140gr. Ballistc Tip, the barrel is right at 25" long and get 3206 fps with 63.5 gr N165, best load I found. Top speed and great accuracy. Seat .010" off the lands. You are informed!!!