Chamber reamer question ?

[clambdin]

I recently had a 280 Ackley built, I told the smith I wanted a SAAMI chamber however fired brass necks are measuring .318 and a SAAMI spec reamer is .315, So I'm kinda confused here ? I will say accuracy is good but I'm still kinda miffed at this..

 

[BountyHunter]

That is why you always buy your own reamer.

If not at least look at the reamer print.

 

[J E Custom]

I recently had a 280 Ackley built, I told the smith I wanted a SAAMI chamber however fired brass necks are measuring .318 and a SAAMI spec reamer is .315, So I'm kinda confused here ? I will say accuracy is good but I'm still kinda miffed at this..

Don't be, he did it right.

.315 is the maximum neck diameter for a loaded round.

.3176 is the chamber dimension for the neck and that's close, I normally will have .004 thousandths clearance in the neck for expansion without pressure.

.003 clearance between the neck of the loaded ammo and the neck chamber is minimum. Most big bores have .006 to .008 clearance when loaded

if your neck brass is thicker than .014 thousandths you may have to turn the necks down to get .003 to .004 thousandths clearance.

.284 + .014 + .014 + .004 = .316

J E CUSTOM

 

[clambdin]

Thank's for your clarification !

 

[shortgrass]

Here it is, agagin; www.saami.org the top print is max cartridge, the bottom one minimum chamber