New Brass and excessive headspace

[jweigel]

If been using Nosler brass in my 7RM and when new it's 5 to .007 short of my target headspace. It takes at least a couple firings to of get it in the ballpark. The problem I'm noticing is extra pressure occasionally.

Is this common?

jjw
ND

 

[Barrelnut]

Was for me in my 300 RUM. The stuff is short for SAAMI specs it seems and that with a cartridge that indexes off the shoulder. Take a case like the 7MM RM that indexes on the belt and that distance from the case shoulder to the chamber shoulder can be even more. Probably wouldn't be a real issue for you unless it was over .010 though. I have seen that with a 7RM Browning chamber.

 

[MagnumManiac]

If been using Nosler brass in my 7RM and when new it's 5 to .007 short of my target headspace. It takes at least a couple firings to of get it in the ballpark. The problem I'm noticing is extra pressure occasionally.

Is this common?

jjw
ND

The 7RM headspaces off the belt, the shoulder plays no part in headspacing on unfired brass.
My 300WM grows .026" in head to shoulder length on unfired brass, the total length of my chamber is .030" above an unfired case. With springback, the .004" poses no problem to case life.

If you are getting high pressure occasionally, it is not due to headspace, headspace has NO effect on pressure.
Brass hardness varies, sometimes, softer brass will show signs of excess pressure while harder brass in the same lot doesn't.
ANY sign of excess pressure, ejector marks, hard bolt lift or sticky extraction means you need to drop the load back a grain or two.

Cheers.
gun)

 

[Corey Schwanz]

New brass is usually on the small side of saami spec if not a little more as it has to be able to fit any chamber out there. Once you fire form it to your rifle, then you have brass specifically for your gun and can really get to work on it. Some people refer to the first firing as the "last step" in the brass' actual creation process

 

[Lefty7mmstw]

New brass is usually on the small side of saami spec if not a little more as it has to be able to fit any chamber out there. Once you fire form it to your rifle, then you have brass specifically for your gun and can really get to work on it. Some people refer to the first firing as the "last step" in the brass' actual creation process

This isn't Jerry's first rodeo. He's worked with me on 7stw loads and we've shot each other's rifles at the local range. He also has a 25-'06 that shoots very well with his loads.

As to your loads Jerry, MagnumManiac is correct that any overpressure symptom is going to necessitate a load reduction, at least for that brass.
I can get you some rem or ww 7rem brass from my leftover stash if you want to work with that for a spell.

I would also look at lesser things like case length and making sure they are identical, powder charge consistency, etc.. Make sure all the ducks are in a row... That rifle wasn't shooting badly at all the last time I saw it in action.

 

[Zen Archery]

Yep. My virgin Nosler Brass always is .005-.007 lower then my shooting specs. It actually takes 2-3 shots (light/moderate load) to form properly. Luckily my rifle isn't too picky even out to its farthest distance about load developments.