284 shehane fireforming question

[its only light]

Hey guys. Just bought a 284 shehane from another member here. Cant wait to get it going. He gave me load data with the gun. The thing is its with lapua brass necked up. I have a pile of winchester brass I'd like to use. Iplan on working up to his velocity nodes with the fireformed brass anyways but my question is the fireforming load.

If I back off from his fireform load will I be ok? I know the brass isn't changing dimension a ton but is there any problems that can occur with to light of a load? Hopefully this isn't a stupid question just want to get it right.

 

[Terry]

Powder & Bullet used?

 

[its only light]

H4831sc and 162 bthp for fireforming load and h4831sc with berger 180 vld. I also have 180 hybrids coming.

I basically don't know what the case capacity difference is between the lapua and win brass. I feel like I should back off from the 54.2gr fireform load but don't know how much and if there is such a thing as too light to form brass?

 

[Terry]

With the 162's 54.2 is plenty light.

I fire formed with 180's jammed at 54 with H4831.
You should have no problem with the 162's and Winchester brass.

 

[its only light]

Great! That's what I was hoping to hear. Cant wait for this below zero stuff to pass so I can go try it out.