Question for the pros...

[J300UM]

I just cracked into a new box of nosler 264 win mag brass. I measured them with my hornady shoulder bump gauge and they were .020" short compared to a fired case from my previous load. After a round of fire forming they are all now .005" short. Should I go ahead and do another round of forming before I begin my new load developement or just start my developement as they are?

 

[g0rd0]

at that length you might as well load them as if they are the right length for you. Then after that you will trim to the exact length that you desire

 

[dig]

Load em, those will shoot fine.

 

[Lefty7mmstw]

Load em, those will shoot fine.

+1


of note though, you are getting ~.015" growth first firing; that is a bit much and brass life will likely suffer... Does the growth calm down after the first firing or does it stay at 15 thou per??

I try to get under .005" per firing growth on any of my rifles. I am rebuilding one partly as it grew .015- .020" per firing.

 

[Mikecr]

J300UM is not talking case length, but head space.
While 5thou short still, I would do full range seating testing(Berger's recommended) during the next fire forming. Then with rough seating determined, and cases at stable capacities, I'd move to powder testing. No other order.

 

[J300UM]

thanks guys. mike pretty much hit the answer i was looking for. i was originally thinking i could do my load developement as they were but would have to change my powder charge once they were at full capacity.

 

[Lefty7mmstw]

J300UM is not talking case length, but head space.
While 5thou short still, I would do full range seating testing(Berger's recommended) during the next fire forming. Then with rough seating determined, and cases at stable capacities, I'd move to powder testing. No other order.

Actually, shoulder bump on a belted is not really a measure of headspace, since primary headspace is on the belt. I was simply asking how long the chamber was in relation to factory brass and how much growth he was getting.... I should have worded the question differently to keep from getting picked apart I guess.

 

[J300UM]

my previous load was with win brass and without looking at my notes i dont believe i had very much growth after the first firing. i was kinda shocked at how short the nosler brass was. i have another box from a different lot and they measured the same. i generally form all my brass before load developement anyways so i wasnt too worried about it.

 

[Lefty7mmstw]

my previous load was with win brass and without looking at my notes i dont believe i had very much growth after the first firing. i was kinda shocked at how short the nosler brass was. i have another box from a different lot and they measured the same. i generally form all my brass before load developement anyways so i wasnt too worried about it.

let 'er rip then...

 

[J300UM]

i should have said i wasnt initially worried about it since i planned on fireforming anyway...