New Brass ... What's Different?

[rustyinbend]

I have a good routine for prepping my fired brass, but I just got a bunch of new brass (Peterson for 300-WM and Lapua for 338-LM). I have two quick questions for the always helpful reloading guru's that hang out here ...

1. Should I do any sizing or other work on new brass before priming, charging, and seating ... or just "Load and Shoot"?
2. Should I disregard the first firing for load, ladder, and accuracy testing, and assume the second firing is the start of usefulness?

Rifle is a Barrett MRAD with barrel conversion kits for 300-WM and 338-LM.

 

[Baron23]

Rifle is a Barrett MRAD with barrel conversion kits for 300-WM and 338-LM.

Can't help you on the brass question, but that's one hell of a lot of cool rifle you have there.

Pics?

 

[Darkside-Six]

I don’t personally size virgin brass but I do run the necks over a mandrel for consistency and chamfer the car mouth.
I think plenty of people do load work up on virgin brass, the main thing is make sure your barrel is “seasoned” and have enough rounds on it that it has speed up.

 

[ShtrRdy]

I usually don't resizing the whole case but I will run an expander into the necks.

You can work up a load in new brass but then you'll need to tweak the load after the brass has been fired.

 

[sinister]

Benchrest-queer stuff:

Test each case for concentricity both before and after loading.



It doesn't help if they're banana-curved before fire-forming.

Check for concentricity after firing. Did the chambering and finishing reamers go in true to the bore? Did cases come out banana-curved in respect to the bore?

 

[Steel head]

Run a mandrel through neck and chamfer.
New brass often gas necks stupid tight.

 

[918v]

I run a big mandrel, caliber size, through the neck to open it up, then size back down using my Lee collet neck die.

Some people say there is going to be an adjustment in powder charge and/or coal when going from new to 1x, but that may not be the case in every instance. Don’t ignore the data.

 

[rustyinbend]

Can't help you on the brass question, but that's one hell of a lot of cool rifle you have there.

Pics?

No doubt ... love my MRAD. Got barrels in 6.5-CM, 308-Win, and 300-PRC too, along with the 300-WM and 338-LM.
With glass and accessories ... I don't even want to "think" about what I have invested in this little firecracker.
Crappy photo, but it's the only one I could find.

 

[rustyinbend]

Sounds like Inspect, Mandrel Neck, De-Burr/Chamfer ... and then it's good to go. Makes perfect sense. Thanks!

 

[NCHillbilly]

I always drop my new cases into a caliber specific case gauge to make sure they'll chamber, then run a mandrel into the case mouth to make it concentric. Check length, if in spec, load 'em up.