Loading virgin brass for fire forming

[silas5150]

Looking for some advice for how to proceed in my particular situation. For context, I am not new to reloading, just new to loading virgin brass.

I have a 338 Norma Mag barrel that I need to start working up some loads for. I bought some Lapua brass and would like to fire form it before I start my workups. Should I just build some cartridges with the "start" loads listed in my manuals? Any reason (safety or otherwise) to do something else?

Finally, with my particular purpose in mind (loading just to fire form), is there any particular brass prep I should perform on the new brass?

 

[Joel Danielson]

Is the barrel new, or does it have some "seasoning"? The reason for the question is that some load data will change from a new barrel as it seasons (usually pick up speed after about a 100 rounds).
New brass I still size before the first firing just to make sure necks are round and close to the same for seating bullets. I would use a lower end suggested powder charge for the initial fire forming, and would seat the bullet .005 into the lands to get a good push back against the bolt face. You will usually get a nice piece of brass to work with for the second firing.

 

[silas5150]

Thanks for the great advice. Barrel is brand new and still needs to be broken in. I normally buy some factory loads to do break in and have a benchmark for load development, but can’t find Lapua brass ammo in stock anywhere.