neck dimensions

[crustyrusty]

I need advice/help with a quandary I have. My 7mm BR and my 280 Rem are both in the smiths hands and are just about done. I want to get ready to do my third rifle(savage axis re-chambered to 280 British) and according to the reamer manufacturer (david manson) the specs for the 280 British call for a .320 neck diameter..1), why is it so large and is it necessary (there is no surplus ammo out here or commercial ammo either) 2), and if I get it reduced to .315 neck what do you think the brass O.D. will have to be? 3,) and do you think there will be a accuracy issue by going to a tighter neck dimension? Or am I making up a problem and should stay with the factory dimension? regards Rusty

 

[338 dude]

I need advice/help with a quandary I have. My 7mm BR and my 280 Rem are both in the smiths hands and are just about done. I want to get ready to do my third rifle(savage axis re-chambered to 280 British) and according to the reamer manufacturer (david manson) the specs for the 280 British call for a .320 neck diameter..1), why is it so large and is it necessary (there is no surplus ammo out here or commercial ammo either) 2), and if I get it reduced to .315 neck what do you think the brass O.D. will have to be? 3,) and do you think there will be a accuracy issue by going to a tighter neck dimension? Or am I making up a problem and should stay with the factory dimension? regards Rusty

.002 to .003 clearance from a loaded round

 

[Rdlningcltchdmpr]

Do you have a dummy round to measure ?

 

[crustyrusty]

I have a dummy round at .320, another at .315, and another at .312 and another at .309 so I don't know which one to use!! I measured a loaded 280 Remington case and it measures .310 with a bullet seated, and it uses a .315 neck. Thats a .005 thou diff.. so using that as an example a .320 neck would use .315 on the cartridge..I have been turning all of my cases between .312 and .310 but I stopped when I realized I could save almost 50.00 if I just use factory spec's and go with a solid point... still would I be better off with the tighter .315 neck or should I stay with the factory .320 neck? or go all the way to a bench rest type of neck and take it to .310?