This is my first time headspacing a savage, I’m removing my 6.5-284 barrel and installing a 6 br. My question is all my brass for a 6 br is shot out of another gun and don’t have any unfired cases, would it be ok to use a hornady oal checker dummy case to headspace with? Or should I just resize a piece of 6 br brass back to spec? I know I should probably use a go/ no go gauge but wanted to try brass first. Thanks in advance for any advice