Guys I'm about to build a trainer rifle and I'm looking for some starting points for development. The barrel is a nss criterion 7twist with a .090" freebore. I plan on using 77gr smk, ramshot tac, and cci primers. I have alot of this on hand and know it's a good combo in my ar. What do you guys have for a setup like this? COAL and charge are my main concerns.